Rebuilding a Chevy Straight Six
Jake is a founder of 8020 Media and has been creating automotive content online since 2017. He has been the lead writer for Chevy Trucks and has transformed it from the old and outdated site it was into what it is today. Jake creates a ton of GM related content for the 8020 Media YouTube channel and specializes in Duramax and Vortec information but has a wealth of knowledge across all GM cars and engines. Jake believes the L5P is the best diesel on the market today.
Rebuilding a Chevy “Stovebolt” Six-Cylinder Engine
Part 1: Removing the inline
Over the years, I have torn up, torn down and tuned up a number of Chevrolet Stove Bolt Six engines. They propelled me everywhere I wanted to go throughout my youth; sometimes under conditions that went well beyond their design envelope. I was 30 years old before I even tried living without a six-cylinder. Other brands of cars have graced my life, but I always missed the inline Chevy sixes. So when the news of an available 235-cubic-inch Stove Bolt reached my ears, I jumped at the chance to take it home and rebuild it. For me this was like finding my favorite boyhood dog alive and ready to play again. Nostalgia may be a factor here, but I also regard this as one of America’s best engine designs. At this point I’m not even sure where this six eventually will reside, but a 57 Handyman wagon in need of a mill would be ideal.
In its early days, Chevrolet’s six was always upstaged by the peppier, more glamorous Ford flathead V-8, even though the Chevy six was a more dependable, less troublesome engine.
Later, when the Chevy six was honed by years of development into the 235 of the mid-‘5Os, it was overshadowed by the company’s own small block V-8, which also is among the best American engines ever produced. Chevy’s mid-’50s Stove Bolt isn’t as powerful as the V-8, but it’s smoother, quieter, and more economical. Best of all, it is dead simple to work on.
Taking it Out
My engine already had been removed from the donor car, but in most instances we aren’t that lucky. So here’s how to extricate yours. Before you begin working on your engine, it s a good idea to scrape off any caked-on grunge with a putty knife, then wash the engine with a strong solution of dish washer detergent and hot water. Wear rubber gloves while doing this. Unless you have a photographic memory, you will want to have a cheap camera with a flash handy so you can take pictures to help you put the car back together when the time comes, and you will want to have a collection of containers or clear plastic bags and a marker pen or grease pencil so you can label and store the many bolts and small parts.
Begin your engine removal by scribing around the hood hinges so you can reinstall the hood in the correct position. Remove the hood and set it aside where it won’t get bumped or dented. Rest it on something soft and cover it with blankets. Next set the emergency brake, block the back wheels and put the front end of the car on sturdy jack stands. Never work under a car while it is on a jack. Doing so is extremely dangerous. A schoolmate of mine was killed when his car fell off a jack many years ago. When you are certain the car is properly supported, get under and drain the coolant, engine oil, and transmission fluid. I like those flat plastic containers with screw-on lids for this type of job. They are convenient and are available at most auto supply stores for a nominal price. Dispose of these fluids at a proper site such as your local service station.
Cover the fenders and grille of your car with old blankets or tarps to protect them. Remove the battery, battery cables and support box to prevent accidents such as dropping tools across the poles of the battery. Label the wires then disconnect the wire harness that runs over the radiator support brace. Gently pull the harness out of the way. Remove the horns. The radiator hose and heater hoses should be taken off next. If the hoses are stuck after removing their clamps, try twisting them gently. If that doesn’t achieve the desired result, slip a slot-head screwdriver under the stuck hose, shoot a little WD-40 into the gap and then gently twist the hose. Dont try this screwdriver maneuver on the radiator end of the hose because its inlets and tanks are made of soft brass, a slip of the screwdriver could cause damage. If you are unsuccessful after a determined effort to twist and pull the hoses off, cut them loose with a sharp utility knife.
If your car has an automatic transmission, disconnect, plug and remove the oil cooler lines. Tape cardboard over the radiator-core cooling fins to protect them. Remove the bolts holding the radiator support to the fender, side baffles, and cross-member, then lift the radiator out. Put it aside where it won’t be damaged. Remove the fan, pulley, water pump, water inlet and thermostat. Save any gaskets, even if they are damaged, so they can be compared to the new ones for accuracy. Disconnect the wiring to the starter, generator, coil and temperature gauge sending unit as well as the ground wire from the engine to the chassis. At this point I also like to remove the starter, generator, distributor and vacuum advance tubing, fuel pump, fuel lines, breather pipe, dip stick, air filter, carburetor and throttle linkage so they won’t get damaged in the process of lifting the engine from the chassis. Disconnect the exhaust pipe and remove the intake and exhaust manifolds.
Many people recommend the manifolds remain in place, but I believe it is safer to remove them with the engine in the car.
Finally, remove the windshield wiper motor to avoid bumping it with the engine and transmission as you remove them. Now get under the car and disconnect the linkage to the transmission and clutch and detach the speedometer cable. If your car is equipped with overdrive, disconnect the wiring and cables to the transmission. Take pictures, label the wires and make notes so you will know how to reattach these items. Split the rear universal joint by removing the four bolts that hold it together, put its bearing bolts back in their yokes and wire its bearing caps together to prevent the needle bearings from spilling out. Pull back on the driveshaft to slip it loose from the transmission. At this point the Chevy assembly manual recommends removing the engine and transmission together. But on cars equipped with standard transmission, I recommend renting a transmission jack and removing the transmission while the engine is still in the car.
After the engine is out you merely need to remove the bell housing in order to mount the engine on an engine stand.
Unbolt one of the upper transmission bolts and find two bolts with the same thread but a couple of inches longer. Cut the heads from these bolts with a hacksaw. Remove both upper transmission bolts and install your two headless bolts in their places These will serve as locator pins that will allow you to slide the transmission straight back to remove it so you won’t damage the clutch or throwout bearing. Screw your transmission jack up under the transmission, strap the tranny to it, then pull the transmission back and out. If your car has a Powerglide or Turboglide transmission, you will want to remove the transmission and engine as a unit as the manual recommends. A cherry picker hoist on casters with an arm that cantilevers over the engine compartment is best for engine removal. Never suspend a chainfall from the rafters in your garage. Even a little Chevy six weighs more than 500 pounds and is capable of bringing the roof down on you.
Remove the valve cover, then loosen a couple of head bolts one at the right front side of the engine and one at the left rear. Attach the lifting chain to these bolts by slipping a link over each of the loosened bolt heads and then tightening the bolts back down. Allow at least 3 feet of 3/l6-inch chain with welded links for this purpose. If the chain is too short, the shallow angle could easily allow the chain to slide forward or backward through the hook of the cherry picker, causing the engine to shift uncontrollably. Also, a short chain will put excessive side loads on the head bolts. And although we’re working with a six in this instance, I’ve found that the two-bolt method is secure enough to remove an engine as large as a Packard straight eight. When you are sure all the accessories are disconnected or out of the way, jack the hoist to take up the slack in the chain, then unbolt the motor mounts.
Be sure to have an assistant handy for this phase of the operation because you’ll need help in guiding the engine as it comes out. Otherwise you could wind up slamming your motor into the sides of the car. Now jack the engine up and out of the car, and roll the hoist and engine out of the way, or roll the car out from under the hoist. The car will rise as you take the weight of the engine off the springs.
If your car came with a standard transmission, remove the bell housing and then attach the engine stand plate to the back of the engine and bolt it securely in place. If your car is Powerglide-equipped, detach the transmission from the engine being careful not to remove any of the torque converter cover bolts which extend through holes in the flywheel. You can place your engine and transmission carefully on your garage floor while you are working on this and use your hoist to lift and move the transmission when you have it separated from the engine. Now attach the engine to an engine stand.
It is easy to determine an engines condition and what rebuilding will need to be done if you disassemble it methodically and know what to look for. Begin by removing the rocker arm assembly. Unbolt it from the head starting from the bolts in the middle and working out to the ends. Break them all loose before removing them. Place the assemblies on a clean workbench.
On a 1957 Chevy, the rocker arms are numbered so it is easy to avoid scrambling them but earlier cars may not have the rocker arms numbered. If they don’t, it is wise to use a punch and stamp numbers into them. There are four different types of rocker arms on a Chevy six including left- and right-hand intakes and left- and right-hand exhaust rockers. Don’t mix them up.
Disassemble the hairpin clips, springs, supports and rocker arms. As you disassemble the rocker arms from their shafts note whether their bearing surfaces are worn and whether their tips are worn where they ride on the pushrods and valve stems. Also inspect the shafts to see if their oil galleries are clogged with dirt and whether they are worn where the rocker arms rotate on them. Replace any worn parts. Clean any sludge or varnish from inside the rocker arm shafts and the oil supply tube using a rifle bore cleaning tool and solvent.
Next you will need to remove the pushrods and valve lifters. But before you do, make a rack for them by drilling correct diameter holes in a piece of 1-by-2-inch wood to hold them in their proper order. It is important that lifters and pushrods go back in their original places when they are reinstalled.
Pull the pushrods out through the top of the head. Clean them with solvent and check to make sure they are straight by rolling them on a flat surface. Note whether their ends are worn. If any pushrods are bent or worn, they should be replaced. Pull the lifters out of their holes. All of the 235-cubic-inch mid-‘5Os Chevrolet sixes were equipped with hydraulic lifters that gave excellent service, provided a fellow changed his oil regularly. If he didn’t, the lifters eventually would get dirty, then begin to wear, and finally collapse. If your engine’s lifters are old, worn or damaged, it’s a good idea to replace them. Here are some things to look for. The plungers in the lifters must be free in the litter bodies. To function properly, the plunger must drop of its own weight when the lifter is held vertically. Check lifters for free fit in the block, and make sure the ends that ride on the camshaft are not worn or pitted.
Worn lifters can be rebuilt, but they must be kept surgically clean during the process. The plungers are matched to their bores, so they are not interchangeable. If your old lifters are good, clean them thoroughly, then store them where they won’t get dirty (a coffee can with a lid works well). If the lifters are not in good condition, rebuild or replace them. (Look for more on lifter repair in our next installment.)
The next step in the engine rebuild process is to unbolt the head. The bolts are torqued into place at 90 to 95 lb.-ft., so you may need a breaker bar or extension to get them loose. If any seem to be stuck, tap on them rapidly with a ball peen hammer. Tapping a putty knife under the bolt head at several points is another way to pop it loose. If you break the heads off of any of the bolts, remove the rest of them, then use a stud remover to remove the broken ones.
After you have removed the head, inspect it for cracks around and between the valve seats. If you find any cracks, obtain another head. Fixes usually don’t work well and heads for old Chevys are easy to locate. Also observe whether there are any cracks in the block, especially between cylinder bores. A cracked block can be fixed but it is usually not worth the trouble on an engine as common as the Chevy six.
If you notice a heavy ridge at the tops of the cylinders, and its likely you will on a high mileage powerplant, it probably means the engine will need to be rebored. The ridge is formed because the piston rings don’t ride up that far so the tops of the cylinders dont wear.
Examine inside the water passages of the head and block. You may notice a rust buildup. If you do find rust use a screwdriver to dig the loose rust out of the head and block. Rust build-up will prevent the free flow of water around the pistons and valves and will cause your engine to overheat. Later your machinist will clean the head and block in the hot tank but it s a good idea to assist with this process by chipping away as much rust as possible.
At this point you may want to disassemble your valves and springs using a valve compressor tool or you may want to wait and let the machine shop take the head apart and tell you what you need. If you disassemble the valves and springs yourself store the little keepers that hold the valves in place in a plastic bag so you won’t lose any of them. The valve springs will need to be tested for proper resilience. Your machinist can usually do this for you. Your valve guides will also need to be checked by your machinist for wear.
Next issue we’ll disassemble the bottom end of the engine, check the cylinder bores, crankshaft, bearings, wrist pins and camshaft for wear, and finish prepping the engine for the machine shop. We will also talk about how to order the necessary parts to rebuild your engine.
Part 2: Disassembling the engine
In our last issue we began a series on engine rebuilding using a 1957 Chevrolet six cylinder as our example. When we left off, we had pulled the engine from the car, removed the manifolds, carburetor and head. We also had disassembled the rocker arm assembly, removed the pushrods and hydraulic lifters and examined all the parts for wear. During the teardown process, we noted heavy ridges at the tops of the engine’s cylinder bores, indicating that it will probably need to be rebored.
In this installment we will concentrate on the bottom end of the engine, which consists of the crankshaft, connecting rods, pistons, cam and timing gears. Many engines have timing chains as well as timing gears, but the Chevy six has only the meshed timing gears.
To begin disassembly of the bottom end of the engine, turn it over on your engine stand so the oil pan is up. Be prepared for a little oil and coolant to run out onto the floor from hidden nooks and crannies in the block.
Loosen the pan bolts, working from the center of the engine out to the ends. Note that there are four larger bolts securing the pan around the front and rear main bearings. When all of the bolts are out, slip a putty knife under the pan and pop it loose. Often, on engines that have been in service for a long time or with those that have been neglected, you will find a great deal of sludge in the pan. If you do, scrape it out and dispose of it properly according to local environmental laws. I usually put engine sludge in an old paint can and set it out next to the trash on special days when the city picks up toxic materials. Your area may have different procedures.
The oil pump comes out next. Disconnect the pipe that connects the pump to the block, but do not attempt to remove the mesh filter and pickup tube on the Chevy six pump. These are installed at the factory and are not intended to be disassembled. Down in the block is a setscrew and nut that holds the pump in place. Loosen the nut, then remove the setscrew. Now pull the oil pump out, wash it with solvent, disassemble and inspect it. Is the pump body cracked or worn? Are the gears worn or damaged? Is the shaft loose in its housing? Check the inside of the cover to determine excessive wear. It should not allow oil to leak past the ends of the gears. Also check the regulator valve plunger. Inspect the screen in the oil pickup unit. Is it torn or damaged? If so, replace it. If problems other than a torn screen exist, you will need to obtain a rebuilt pump, because these items are not rebuildable by the home mechanic.
You can obtain a rebuilt pump from an antique parts supplier such as Egge Machine in Santa Fe Springs, California. Egge will be the source for most of our components on this project (see info below on Egge).
The next challenge will be to remove the harmonic balancer from the front of the engine. The manual says to use Chevrolet tool 1287, but an ordinary gear-puller will remove it just as easily. Generic gear pullers come with an assortment of bolts for different applications. For this project we selected two 3/8-inch x 16 bolts of the correct length and put them through the appropriate holes in the puller, then into the holes on the front of the balancer. Make sure you tighten them enough to avoid having them pull out and strip the threads in the balancer when you tighten the puller. Also make sure you tighten them evenly so the crosspiece of the gear-puller is parallel to the gear. Otherwise you will pull on the gear at an angle and possibly cause some damage. Now tighten the puller slowly until the harmonic balancer pops off. Be careful – it may come off with considerable force.
Remove the timing gear cover by loosening all of its screws evenly, then removing them. Note that, on the Chevy six there also are two bolts that attach from the back of the cover through the front main-hearing cap. Save the screws and bolts in a labeled coffee can or jar. Next remove the smaller crankshaft timing gear using the same gear-puller as you used for the harmonic balancer or if you just happen to have a set of those special Chevrolet engine tools use number 8105 which will do the same job in the same manner.
Turn the large fiber camshaft gear until the holes in it line up with the screws that hold the camshaft thrust plate in place. Insert a screwdriver through the holes and remove the two camshaft thrust plate screws. Support the cam at the back of the engine with one hand so it won’t damage its bushings on the way out, and then carefully slip the cam out the front of the engine. The cam lobes and bearing surfaces should be shiny and free of grooves or evidence of wear. If the cam is seriously worn, it will need to be replaced. When it’s time to take the engine components to the machine shop, the cam will need to be more carefully checked for wear with a micrometer, then Magnaflux tested to check for cracks. It should also be straightened if necessary.
Never lay a cam, or crankshaft, on its side when storing it. If you do, there is a good chance it will warp from its own weight. Stand the cam on end using the timing gear as a base. Strap it to a post in your garage using coat hanger wire to keep it from being knocked over. Chevy cams are long and are made of cast iron alloy, so they can crack, or even shatter, if dropped. The crankshaft also must stand on end and should be supported by wiring it to a vertical framing joist or post in your garage.
Before removing your engine’s pistons and connecting rods, mark them with a file or punch so you can remember their cylinder number and positioning in the cylinder. Most pistons were made of comparatively soft aluminum by 1957, so marking them is easy but requires some care on your part. Gently tap the punch when stamping in the identifying numbers to avoid any damage. (The usual procedure is one dot for the number one piston, two dots for number two, etc.) Also make sure you punch all numbers in the same location on the piston, so you will know which way the piston is supposed to face when reinstalling it. The future usefulness of your old pistons however will depend on the overall condition of the engine. If your engine is worn and requires reboring (as is often the case) you will have to install new oversized pistons to fit the larger bore.
To conveniently work on the connecting rods and crankshaft, turn the block upside-down in your engine stand. Number the connecting rod end caps as you did the pistons using a punch or small file. Each connecting red end cap must go back on the same rod and be placed so it’s facing as it did originally. If you need to turn the crankshaft while working shoot a little light oil onto the cylinder walls then try to turn it with your hands. If you cannot move it use a piece of wood to pry against the balance weights to move it.
When I go to the trouble of taking an engine apart I usually rebuild it completely although doing so is not always required. If your engine had good oil pressure before you tore it down, the rod and main bearings may not be badly worn and it’s not absolutely necessary to replace them. Inspect them for wear, pits, scoring, galling or other damage, and if they appear to be in good condition, you can further check their clearances with Plastigage. This product is available at auto parts stores, and consists of a tiny plastic rod inside a paper envelope. To use it, merely place a bit of the plastic on the crankshaft journal, then torque the rod bearing cap into place. (The torque Specification on a ’57 Chevy six is 35 to 45 lb.-ft.)
Do not turn the crankshaft with the Plastigage in place, as it will distort your reading. Now remove the bearing cap and use the accompanying paper to check the bearing’s clearance. If it is between .001-inch and .004-inch, the clearance is still satisfactory provided the Plastigage is flattened evenly. If the squashed plastic is wider at one end than the other, your crankshaft may be worn. If the clearances on your rod bearings are greater than .004-inch they are too loose and will not hold sufficient oil pressure. If your bearings are still serviceable, you’re lucky. Most of the time, if your engine has to be torn down for an overhaul, it is also necessary to have the crankshaft turned at a machine shop and then install undersized rod bearings to fit it.
To get the rods and pistons out of the engine, you merely need to remove the connecting rod end caps and push the pistons through the top of the engine. Wrap the ends of the connecting rods with old socks or several layers of duct tape to keep them from scraping and scoring the cylinder bores when pushing them out through the bores. If the pistons hang up on a ridge at the top of the cylinders you will need to obtain a ridge cutter or reamer, available from an automotive tool store. Adjust the cutter so it will only cut a little at a time, then squirt light oil onto its blades. Now turn the cutter in each bore until the cylinder ridge is removed. Wipe up any residue or shavings with a rag.
Part 3: Prepping for the engine shop
Last month in the Weekend Wrench we completed the disassembly of our project engine. We pulled the harmonic balancer, then removed the timing gear from the crankshaft. We checked the rod and main bearings for wear. We removed the cam, marked the pistons and the rod bearing caps, and reamed away the ridges at the tops of the cylinder bores. Finally, we pushed the pistons and rods out through the top of the engine block and removed the crankshaft.
What’s ahead for us will require a few machinist’s hand tools. They will help determine the amount of restoration work needed to revitalize our tired old mill. In the end we will trust a good machine shop to make the final calculations and run some tests to tell us what needs to be done, but by checking things ourselves, we will have a good idea of what the engine requires. What’s more, we may save some money by doing so.
To determine what your engine needs, you will need to take some critical and precise measurements. A few thousandths of an inch one way or the other between the cylinder bores and the pistons can mean the difference between a quiet, dependable engine, and one that may seize when warmed up or has piston slap due to loose tolerances. If the cylinders and pistons have more than .0011-inch clearance on an engine like this Chevy six, the pistons will be too loose and will wobble in their bores, as evidenced by a rapid clicking when the engine is revved. If the pistons are too tight in their bores, (under .0005-inch clearance) the engine will seize when the pistons expand as they reach operating temperatures. Either scenario (too tight or too loose) is bad news, and unless you check these clearances carefully while overhauling your engine, you won’t know about these problems until it’s too late.
Other parts need to be measured as well. If your crankshaft is worn, or out-of-round, its bearings will not hold oil pressure, may be noisy, and will be prone to failure. If your engine’s cam is worn, the valves may not open far enough or stay open long enough. If your cam bearing journals are out-of-round by more than .001-inch, the cam will need to be replaced or reground.
So how do you take the necessary measurements? It’s fairly easy, but it requires a certain feel and a few special tools. You’ll probably find what you need at your local tool store. After youve rounded up the tools, have an experienced machinist help you develop the correct feel and show you how to read the scales. If you don’t know a machinist, double-check your feel and accuracy by first measuring items of known dimensions, such as feeler gauges or pieces of machined metal stock. Make sure the object you are measuring whether you re practicing or doing the real thing is clean and the blades of your tool are clean as well. A tiny bit of dirt can easily throw off precise measurements.
An engine block is seldom worn out. The exception may be if it came out of a Havana taxi cab. If a block is not cracked or corroded it usually can be machined to specs and even made better than new. I say it can be better than new because new engine blocks are green in the vernacular of racers and rebuilders. In other words, the casting process creates various types of stress in a new engine block that can take months to work out. These metal stresses combined with continual heating and cooling can result in warping of the block.
Your rebuilt engine also may turn out better than new because until recently most domestic manufacturers tolerated less than rigid quality control procedures on their engine production lines. Hot rodders and racers who wanted their engines to stay together at high RPMs came up with the accurate machining and balancing techniques that can improve the older powerplant in your vehicle.
But before we take measurements, let’s rule out some obvious problems. Are there any noticeable cracks between the cylinders? Are there any cracks around the main hearing saddles? Are the water jacket openings for the head corroded away? Are the soft plug openings (also called freeze or expansion plug openings) severely corroded and damaged? If you find any of these problems, get another block. Such things can sometimes be fixed, and if you are overhauling a Duesenberg straight eight you will certainly want to try, but with an engine as common as a ’57 Chevy six, finding a good alternative block is the best and cheapest answer.
Even if you can’t see any cracks in the bearing journals or cylinder walls with the naked eye, there still may be some. Check for smaller cracks by using a product called Spotcheck from the Magnaflux Corp. With the Spotcheck system, a cleaner is first used to prepare the surface. Then a penetrant in the form of a liquid red dye is applied followed by a white powder that makes cracks stand out. Spotcheck also can be used to discover cracks in heads, rods, pistons and crankshafts. It is especially good for nonmagnetic parts, such as aluminum pistons, that cannot be tested by the traditional Magnaflux methods used at most machine shops.
If your block is not cracked or corroded, chances are it is rebuildable. Next check the deck, the mating surface for the head. Start by cleaning it of all remnants of gasket sealer, carbon and dirt. Now place your steel ruler on edge along the length of the block. Shine your trouble light behind the ruler and if you see a gap or gaps, check them with a feeler gauge. If they are more than .007-inch wide at any point, the deck will have to be milled (planed flat). Place the straightedge across the engine deck it several different angles to complete this check for warping.
Next check the taper in the cylinders. Engine cylinders that have accumulated many miles will be worn bigger near the top than at the bottom. That’s because the rings on the pistons slide up and down only in the upper parts of the bores. checking taper can be done with a bore-measuring tool or an inside micrometer. If the bore-measuring tool has a dial-type indicator, run it slowly up and down the bore and note the change in diameter. If it is greater than .005-inch, your engine will need to he rebored. If it is under .005-inch and your pistons are good, try cleaning the bores with a cylinder hone (available from auto parts stores), then install new rings on the pistons. If you measure your engine’s taper using an inside micrometer, measure near the top and near the bottom of each cylinder. Place the micrometer in each bore, then rock it back and forth a little to find the minimum straight-across measurement.
Next measure your cylinder bores for roundness. As engines run, pistons pivot on their wrist pins and can cause uneven wear at the sides of the cylinder bores. Also, most aluminum pistons are cam-ground to a slight oval shape with the widest dimension along the axis of the wrist pin. This is done because the steel wrist pin limits heat expansion. The areas of the piston perpendicular to the wrist pin are ground smaller to allow for greater expansion. As the engine heats up while running, these areas expand more because there is nothing to restrain them. All of these factors can effect cylinder roundness.
To check for roundness, take measurements near the top and near the bottom of each bore. Then measure at right angles to these first measurements. Your cylinders should not be more than .005-inch out-of-round. If they exceed that tolerance, have them rebored at a machine shop.
If your engine block needs to be rebored, you will need to replace your old pistons with new ones in a larger size. The usual over-bore sizes are: .020-inch, .030-inch and .040inch, but let your machinist tell you which size to buy after he has determined how much it will take to clean the cylinders. If you are lucky and your cylinders only need honing, you may be able to use your original pistons, or if you can find a set of the .001-inch oversize pistons that were originally made for this situation, you can install them.
If your crankshaft’s main bearing journals are out-of-round more than .001-inch or are tapered beyond the same figure, the crankshaft will have to be turned and the appropriate undersize bearings installed. Use a Vernier caliper or an outside micrometer to check the journals. Also make sure the journals are not out-of-round by checking at 90 degrees to your first measurement on each journal. Replacement bearings are generally available in .010-inch, .020-inch and .030-inch, but let your machinist make that determination.
Connecting rod journals need to be checked the same way. If they are tapered or out-of-round by .002 inch, they will have to be ground and undersize bearings fitted. Again, let you machinist make the call. Incidentally, don’t be tempted to file the connecting rod end caps to tighten the rod bearing clearances, as was done on older engines. Rapid bearing failure may result.
The lobes on your engine’s cam should be shiny and without any trace of grooves, discoloration or cracks. If these tell-tale signs of wear are apparent, the cam should be reground and Parkerized, a procedure where the cam is heated and then dipped in a solution that hardens the surface and protects against corrosion. If its bearing journals are .001-inch or more out-of-round, the cam will need to be ground and undersize bearings fitted. On a Chevy six, as well as many other engines, each bearing journal is slightly smaller in diameter from front to back in the block. It was designed that way so the cam can be installed and removed from the front of the engine. Check your shop manual for the correct diameters for these journals.
A Second Opinion
After making the measurements outlined above, you will have a good idea of what your engine will need, but don’t whip out your credit card just yet. First, take your parts to a good machine shop and have your findings verified. Let the machinist tell you how much your block will need to be bored and how much your crank will need to be turned so you can get the appropriate replacement parts. When you take everything in to be machined, don’t forget to take your flywheel and clutch as well. Chances are your flywheel needs resurfacing, and you will want the clutch and flywheel attached to the crankshaft during balancing so the whole assembly can be balanced as a unit for maximum smoothness.
How do you find a good machine shop? Start by asking members of local car clubs, particularly those familiar with cars like yours. Also check with local hot rodders. The chrome-valve-cover fraternity usually knows who does good work in the area. you might also try local garages and auto parts dealers for recommendations. Finally, visit the machinist’s facility before you entrust your precious classic parts to his care. Is the shop clean? Are the machines fairly new and in good working order? (Old machine tools can be notoriously inaccurate.) Do the guys working there show a flicker of recognition when you utter the name Studebaker, or do they only know about cars made after 1990? Determining the answers to these key questions can make a big difference in the outcome of your job.
Between now and next issue, we will be consulting our own machine shop and getting the verdict on our old Stove Bolt. Stay tuned, because we will talk about such things as setting up your engine for a diet of unleaded fuel, which kinds of pistons and bearings to buy, and valve guide selection as well.
Part 4: Reassembly
Last month the Weekend Wrench demonstrated how internal measurements can help you determine what work needs to be done on your engine. It explained ways to check for cracks in the heads and block and suggested methods to identify a good machine shop. This last step is especially important because the dialogue you establish with your machinist, and the quality of work he does, will go a long way toward ensuring smooth and long-lasting engine performance.
You will want to discuss such things as whether to install hard, insert valve seats in your engine’s head, (or block, in the case of a flathead) whether to install special, no-lead valves, and whether to install bronze valve guides. Chances are, unless you only drive short distances under light loads you will want your old valve seats machined out and modern valve seat inserts, designed for no-lead fuels, put in, or you may want to install no-lead valves. You dont need both new valve seat inserts and no-lead valves though, because either of them will provide the protection you need for daily driving with unleaded fuels.
Generally speaking, the installation of new valves is the less expensive way to go. Furthermore, some engines have rather delicate valve seats that cannot he machined to install inserts. Your best approach is to consult your machinist as to which is preferable for your application. While your at it, don’t forget to talk to your machine shop mechanic about bronze versus iron valve guides for your application as well. The softer bronze guides may be preferable for flatheads, which often have trouble getting enough oil to that portion of the engine. But for overheads, which generally don’t have that oiling problem, the harder iron valve guides usually are preferred because they’ll give you longer wear.
Regardless of whether you have checked the head, deck, and bearing saddles for cracks, your machinist should also conduct a Magnaflux test, just to make sure nothing was missed. During a Magnaflux test, the engine part is subjected to a strong magnetic field and small, metallic particles are sprinkled on the component’s surface. The small particles tend to collect on any cracks in the surface.
This test is far preferable to finding out about a hidden crack after you’ve had a lot of expensive machine work done and then assembled and reinstalled your engine. Chevy six heads are notoriously prone to cracking, so if you are doing one of these engines, have the head checked carefully, and find another one if your original has problems. Don’t forget to have your machinist balance your engine, too. Pistons vary in weight and should be matched up at a machine shop by drilling out small portions of metal until they are all equal. Crankshafts should be balanced with the flywheel and clutch installed, so the assembly will spin smoothly as a unit, with no vibration. Cams, crankshafts and connecting rods should be straightened as needed at the machine shop.
Buy the Parts
Once your machinist has told you which undersized bearings and what size pistons you will need to compensate for wear and machining (see “Does Your Engine Measure Up,” Part 3 – December 1995), and you decide which kinds of valves, or inserts you want installed, call an antique auto parts supplier and give them your laundry list. Don’t forget to buy a gasket set too. And just to be on the safe side, you may want to order a rebuilt water pump, oil pump and fuel pump as well. I purchased my engine parts through Egge Machine in Santa Fe Springs, California (address for Egge is listed in Part 2). Paint your engine’s parts before you start the assembly process.
If you are doing a Chevy six like our project engine, you will want to have the machine shop press new timing gears onto the cam and crankshaft. Also, if you’re doing a Chevy six, consider installing an aluminum crankshaft timing gear instead of the original fiber type if you are going to use the car as a driver. The aluminum gear will be a bit noisier, but it will hold up better. On engines equipped with a timing chain, you generally can install these gears by hand, so check your shop manual or machinist for your application.
Before reassembly, clean the engine carefully to remove machining debris. This also provides an opportunity to closely examine the engine and make sure the machining work was done correctly. Wash the outside of your engine with lacquer thinner, then, using a rifle bore cleaning kit, scrub all the little oil passages in the block: Dip the bore cleaning swabs in light oil then work them up and down the passages. Keep cleaning until all of the metal shavings and dirt from the machine work are removed. When your cotton swabs emerge white after inserting them all the way into the passages, the galleries are clean.
Now thoroughly clean the cylinder bores and bearing journals with rags and light oil. The grit left from the machining operations can cause your engine to wear rapidly. Any foreign substances will be carried throughout the engine by the oil, so shavings in the block can find their way to the bearings and ruin them too.
When everything is impeccably clean, paint your engine’s block, head, pan and other components, so when you assemble them the edges of the gaskets will not have any traces of paint. Judges and knowledgeable friends are likely to knock you down a few points if your car has painted gaskets. Cover flecks and mating surfaces with cardboard or stiff paper cut roughly to size. Since this type of painting generally is done with aerosol cans, you don’t have to worry about taping the cardboard in place. Before painting the sides of the head, set the valve cover, which is the same color as the engine anyway, in place to protect the rocker arm assemblies from overspray, and install an old set of spark plugs to keep paint off of the plug hole threads. Paint the side plate, bell housing and clutch inspection pan too. Let your parts dry a day or two before proceeding. Naturally, you’ll want to have the correct paint for your model, year, and engine type. An automotive paint supplier can help you in that regard.
Start checking the machine work by inserting the pistons, one by one, into their holes alongside a long, 1/2 inch-wide feeler gauge attached to a fish weighing scale. On the Chevy six engine, you need a gauge .0015 inch thick. For other engines, check your shop manual for the specified clearance between the piston and cylinder wall. Insert the feeler gauge at 90 degrees to the wrist pin. Now insert the piston and gauge until the piston pin is half way into the cylinder.
Pull out the gauge using the fish weighing scale. If the scale reads between 7 and 18 pounds, your pistons are within tolerance. If your scale reads lower than 7 pounds, your pistons are too loose. If your gauge reads higher than 18 pounds your pistons are too tight. If they are too tight, you can probably have the machinist hone the cylinders a little so they will fit. If they are too loose you may need to have them knurled to size or go to the next larger size piston and have the engine bored again.
Don’t be tempted to put your engine together if the tolerances arent right. If the pistons are too tight, they may seize when the engine reaches operating temperatures, or at the least the engine will be very hard to start when warm and the pistons will wear quickly. On the other hand, if your pistons are too loose, you will have annoying piston slap and your engine will burn oil.
Check your piston rings in their lands on the pistons using a feeler gauge to insure that they have the correct clearance. On the Chevy, the fit around the compression rings should be between .0020-inch and .0035-inch. The oil ring is okay if it has no less than a .010-inch clearance. Also check your compression ring opening gaps by slipping the rings into a cylinder bore one by one and squaring them with a piston inserted upside down into the bore. The gaps should be .007-inch to .0020-inch when measured with a feeler gauge.
Before you begin assembly of your engine, pick up a shop manual for your car and study the procedures. Each engine is different so no set of general instructions will completely suffice. Also work methodically and carefully and keep in mind that when it comes to building engines the old song title “Little Things Mean a Lot” very much applies.
With that in mind, start by smearing the cam bushings (these usually are pressed in at the machine shop) with a thin coat of assembly lube, then carefully slide the cam into place. Be careful not to bump and damage the bushings. Roll the wick seal into the rear main bearing using a round dowel and working from the ends to the center. Using a sharp single-edged razor blade slice off the excess seal exactly level with the mating surfaces. You can use a piece of wooden dowel the diameter of the rear main bearing to help press the seal into place and to hold it while you are working on other things.
Clean the end cap bearing journals as well as those in the block with lacquer thinner. This is important because one bit of grit will cause a deformity or bump in the bearing shell which will cause heat, friction, and early bearing failure due to insufficient clearance. In addition oil or grease on a bearing saddle will make it more likely for the bearing to spin in its journal and may upset tolerances as well. Slip the main bearing shells into place in the main bearing saddles and end caps.
On Chevy sixes, be sure to install the upper bearing halves so the smaller of the two oil holes will be toward the camshaft when the bearing halves are rolled into place. If you are working on another kind of engine, check your shop manual for the correct procedure for your car.
Once they are in place, smear the bearing surfaces with a thin coat of assembly lube, or motor oil, then get a friend to help you set the crankshaft gently back into place, making sure that its gear teeth mesh with the timing gear on the cam and that the little timing marks on the gears line up properly. Next, smear a little assembly lube on the bearing surfaces of the main bearing caps, and tighten the special, self-locking pal nuts. Never use ordinary nuts on main bearings, as they would come loose in service and wreak havoc with your engine. On our Chevy six, three fresh .002-inch shims need to be placed under either side of the intermediate main bearing end caps. Then the main bearing caps are evenly torqued in place. This is accomplished in three stages working in rotation until theyre torqued to 100-110 foot pounds. (This spec is for the Chevy six – your engine may vary.)
Turn the crankshaft using your hands. You should just be able to rotate it with some effort. If it turns easily, it is too loose. If it won’t turn at all, it is too tight. If you have either problem, check your bearing clearances with Plastigage. Be sure to wipe the bearings clean, then follow the instructions on the package. Bearings that are too loose will not hold oil pressure. Bearings that are too tight will not get enough oil. Either situation will ruin the bearings.
Before installing the pistons and rods, check the end play in the crankshaft by forcing the crankshaft all the way forward or aft, then slipping a feeler gauge between the bearing end cap and the base of the crankshaft counterweight. The reading should be between .003-inch and .009-inch. If it is not within tolerances, replace the rear intermediate main shells and check again. Also, on the Chevy, check the lash between the timing gears with a feeler gauge. It should read between .004-inch and .006-inch. Install the rings using a ring expander, and be sure to arrange them so their gaps are in the correct positions according to your shop manual. The three-piece, oil-saver oil rings are a good idea on most engines.
Wrap the big ends of your rod bearings with rags and tape so they will not score your cylinder bores or damage your crank journals while you are installing the pistons. Coat the cylinder bores with motor oil. Using a ring compressor, slip the pistons into their bores, making sure they are facing the correct direction. (On a Chevy six the piston pin clamp must face the camshaft side of the engine.) Gently push or tap the pistons down into their bores but be careful not to damage your crankshaft by bumping it with the big ends of the connecting rods.
Again clean the bearing saddles on your connecting rods with lacquer thinner making sure to remove all grit and dirt. Slip the insert bearing shells into place then coat them with assembly lube. Install the bearing caps making sure the numbered side is toward the camshaft on the Chevy or follow your punch reference marks if your engine has no reference marks. Now torque the end caps using only self-locking nuts to 35-45 pound-feet of torque. Tighten them evenly in three stages.
Look over the job carefully and make sure you haven’t forgotten anything and be sure to wrap your engine in heavy plastic when you quit working for the day so no dirt or grit can invade.
Next we’ll install the valve train and head.
Part 5: (Reassembly, part 2)
In the last installment of our engine rebuild series, we cleaned the block and bearing saddles and reassembled the bottom end, which included the installation of the cam and crankshaft, pistons and connecting rods. This month we will finish building what is commonly referred to as the short block, or the engine minus its accessories.
Before we start on the top of the engine, we need to install the oil pump and its basket, then attach the pan. Rotate the engine on an engine stand so it is at about a 45 degree angle with the top of the engine upwards and the crankshaft portion down. Now fill the oil pump with fresh 10-30 oil, rotate its gears, and refill it. Slip the pump into place in the block and tighten its attaching lock screw. Make sure the tapered end of the lock screw goes down into the hole in the oil pump body, and then tighten the lock nut securely.
It is necessary to fill the oil pump so the engine will develop oil pressure quickly on its initial startup. If you don’t fill it, there is a risk that your engine won’t develop oil pressure in the first critical seconds of its running life. This could result in scored cylinder walls, burned bearings and even a ruined engine.
Install the oil lines and filter basket assembly. Make sure the lines to the oil pump are properly installed to eliminate the possibility of pump shaft seizure when the lines are tightened in place. Another note of caution: If the mesh in your pickup basket is torn or damaged, replace it or find another basket. On many vintage engines oil cleansing is minimal. As time goes by, if you should neglect to change your engine’s oil, torn mesh in your oil pump pickup basket could allow larger particles of contamination to enter oil galleries, block them and starve the rod and main bearings for lubrication.
Once the oil pump assembly is in place, it is time to install the pan. Lay the gasket on the pan to make certain it fits correctly. Sometimes gaskets have two distinct sides with one meant for the pan and the other for the block. Smear the pan’s mating surface and the mating side of its cork gasket with a thin coat of silicone sealer. Let the sealer get tacky. Now gently press the gasket into place on the pan and position it carefully. Do not coat the bottom of the block or the top of the pan gasket with sealer. It is not necessary to prevent leakage, and besides, you may need to remove the pan at a later date.
Gently place the pan on the engine block and hold it in position while you loosely install two or three of its bolts. Install the rest of the bolts loosely. Snug them up evenly in a couple of stages, working from the center of the pan out to its corners. Check your manual for proper bolt torque figures and don’t over-tighten. If you tighten the pan bolts too much, the cork gaskets used on many engines will be excessively compressed and therefore ruined.
Timing Gear Cover and Harmonic Balancer
Before you attach the timing gear cover, make sure the cover has a new seal where the harmonic balancer goes through it to the crankshaft. Coat the cover’s mating surface, both sides of its gasket, and the mating surface of the block with silicone sealer and allow the sealer to become tacky. Now slip a centering tool, (Chevy made a special tool for this purpose, but good luck finding one) made from a piece of correct-diameter tubing, over the end of the crankshaft, then slide the timing gear cover into place over the tool. Don’t attempt to install the timing gear cover without some kind of centering tool, because its seal must fit evenly against the harmonic balancer to prevent oil leaks. Install the cover screws loosely, then tighten them evenly in a couple of stages to between 6½ and 7 lb.-ft. of torque. Again, don’t over-tighten because you may develop oil leaks from a deformed gear cover if you do.
The harmonic balancer goes on next. Smear a little grease on the seal. Now line up the harmonic balancer on the keyway of the crankshaft. Use a hammer and drift, a round soft metal tool, to tap the balancer evenly into place until it bottoms against the crankshaft gear behind it.
Head and Rocker Arm Assemblies
On engines with overhead valves, the machine shop usually seats the valves and installs new valve guides, valves and springs. Before mounting the head on the block, however, it’s a good idea to check the shoulder heights of the valve guides. If the valve guides are too low in the head, valves can stick. If hey are too high, the valves may lot seat correctly. Check the shoulder heights of the valve guides by lacing a steel machinist’s straight edge next to the valve springs. Check your shop manual for the correct height for your engine.
Inspect the valve keepers to make sure the machine shop used new ones when installing the valves. In overhead valve engines this is critical, because if a valve keeper breaks, your engine may swallow a valve while it is running. This will give it a terminal case of indigestion and possibly ruin your block.
Now turn the engine upright in the engine stand. Inspect the deck mating surface on the block for the head, and make certain the piston tops and bores are completely clean. Although we cleaned these areas in our last installment and covered the engine with a plastic tarp when we weren’t working on it (January ’96), if any particles of debris are found, wipe down the areas with soft cloth and some lacquer thinner or WD-40. Even a little grit or dirt can wreak havoc with a new engine. Place the head gasket on the engine and make sure it has all the required holes and they line up correctly with those on the block.
Fashion a couple of guide pins to help install your engine’s head. Pick up a couple of extra long bolts at the hardware store that have the same threads as your head bolts and cut their heads off. Using your fingers only, tighten them into head bolt holes on either end of the block so they can act as locator pins for your head and head gasket. Before going on to the next assembly steps, put an old set of spark plugs in your engine’s head to help keep out dirt. (Use old plugs because they may be bumped and damaged during the assembly process.)
Coat the head gasket on both sides with a good sealer such as Gaskacinch; make sure you have the gasket perfectly aligned so all the bolt holes and water passages are open, then gently press the gasket into place on the block. Set the head on next. If the head on your engine is a long, heavy, cast iron type like the one on our Stove Bolt six, get a friend to help you lower it on so you won’t accidentally dent or deform the gasket. Coat the head bolt threads with a little Permatex or silicone sealer, tighten the head bolts into place with your fingers, then remove the guide pins and install the last two bolts.
Using a torque wrench, tighten down all the head bolts evenly in three stages to the correct specification following the bolt-tightening sequence shown in your shop manual. If you don’t have a tightening sequence diagram to follow for your engine, start at the center of the head and work out toward either end of it, alternating back and forth as you go. The head bolt torque specification for our little Chevy six is 90 to 95 lb.-ft. of torque, but other engine’s specs may differ.
Lifters, Pushrods, Rocker Arms
Make sure hydraulic lifters are filled with oil, coat the lifters lightly with oil, and then drop them into their holes. If you are reinstalling your old lifters, put them into the same holes they came from, as they will mate best with their original pushrods. Now oil the ends and set the pushrods into place above the lifters. If you are using your original pushrods, put them back where they came from as well.
The rocker arm assemblies go on next. In a previous installment of our engine rebuilding series (October ’95), we discussed cleaning, reassembly, and making sure they are kept in sequence. On a Chevy six, as on many older engines, there are four types of rocker arms. (They include separate right and left exhaust and intake configurations.) To assure proper alignment to the valve stems, the rocker arms must be arranged in their correct order. Make sure the pushrods are seated in the rocker arms, then tighten the rocker arm assemblies evenly into place using a torque wrench. A common torque rating for these bolts is 25 to 30 lb.-ft.
The technique and specifications for preliminary valve adjustments vary depending on year and make as well as whether an engine has hydraulic or mechanical lifters. The job usually involves bringing each cylinder up to TDC (Top Dead Center) then adjusting the gaps between the ends of the rocker arms and the ends of the valve stems to the specifications stated in your shop manual.
Coat one side of the valve cover gasket and the mating surface on the valve cover with silicone sealer allow them become tacky and press the gasket into place. Set the valve cover on the head and install its bolts. Snug them evenly in two stages, but again, don’t over-tighten. Attach the engine side plate using the same technique. In both cases, only use sealant on one side of the gasket so you can remove these panels later. The oil pressure in these areas of the engine is minimal, so you won’t have leaks, even without sealer on both mating surfaces, providing the gaskets are evenly tightened into place.
In the case of our Chevy six, the intake and exhaust manifolds are attached, as was common practice on inline engines of the past. Such integrated manifolds should be taken, still lofted together, to the machine shop so their mating surfaces can be planed flat. Long manifolds on inline engines are prone to warping. If they are not planed during an overhaul, they may crack from stress when tightened back onto the cylinder head. To reinstall manifolds on an inline engine, attach them loosely, then – with the manifold pilot sleeves and gaskets in place – attach them loosely to the head. Tighten everything evenly in three stages working from the center of the manifolds out to the ends. Check your shop manual for the proper torque. On our Chevy, the center clamp bolts require 15 to 20 lb.-ft. of torque, while the two end clamp bolts require 25 to 30 lb.-ft. of torque.
In the next issue we’ll complete our assembly procedures, attach the bell housing and flywheel, and reinstall our engine. There will also be tips on starting your engine for the first time.
Part 6: Finishing and reinstalling the engine
It’s taken us five installments, but we’ve finally come to the point in our engine rebuild series where we can install the distributor, clutch, and various pumps and accessories, set the engine back in the car – and enjoy the smooth performance of a restored powerplant.
Clutches are inaccessible once the drivetrain is back together, so it is advisable to install a new clutch disk, and a new, or rebuilt, pressure plate assembly and clutch release bearing (throwout bearing) any time you have an engine out of a car for overhaul. Take your old clutch assembly to the parts house and have them match the parts. Surprisingly, clutches for cars made during the past 5O years are fairly easy to locate, because most manufacturers’ products, such as Borg and Beck, Long and Chevrolet were used in several makes for years at a time, without change.
If you haven’t refurbished your flywheel, do it. Flywheels take the heat in cars equipped with standard transmissions. They often warp, become glazed, or even crack. In a previous installment (Part 3 – December 1995), we advised that a flywheel be resurfaced at the machine shop while your other engine parts are being machined. We also recommended that, after the flywheel is properly surfaced a new, or rebuilt clutch assembly be attached and the components balanced to prevent vibrations during acceleration. Also, both the clutch assembly and the flywheel should be marked, so you can put the clutch on the same way it was when it was balanced.
Bolt the bell housing (also called the clutch housing) onto the engine, making sure any shims are reinstalled as they were when you disassembled the engine. Bolt the flywheel onto the crankshaft of the rebuilt engine with new bolts of the correct hardness, (check your manual for hardness specs or inquire at a transmission shop) and use new lock washers or other locking devices as required for your application. Evenly torque the bolts to the correct specifications according to your shop manual. (On our Chevy the torque is between 55 lb.-ft. and 65 lb.-ft.) Never attach a flywheel to an engine with ordinary, hardware store bolts. It is possible such bolts will break, and a loose flywheel can explode like a hand grenade when subjected to high revs.
With the help of a pilot tool (available at auto parts stores), slip the clutch disk in place against the flywheel. Attach the clutch assembly to the flywheel and evenly tighten its bolts one-half turn at a time, to the correct specs for your make. If you don’t tighten the clutch assembly evenly, you run the risk of distorting it. Remove the pilot tool, then lubricate the pilot bearing (it’s the little bushing in the center of the flywheel) with graphite grease. Don’t overdo it. Too much can leak onto the clutch lining ruining it. Pack the throwout (clutch release) bearing with grease and slip it into its yoke. put a little grease on the yoke pivot point too. Make sure you install the throwout hearing facing the right direction. More than one mechanic has put a bearing in backwards, and damaged the clutch and bearing when he ran the engine.
On some cars, it is easier to attach the transmission to the engine while they are both out of the car. With our six-cylinder, standard-shift ’57 Chevrolet, installing the transmission is easier after the engine is in the car because there are no crossmembers in the way of the transmission.
However you do it on your car, here are some installation tips. Put the transmission into high gear which is direct drive. Put locator pins into the upper bell housing holes. These can be fashioned by cutting the heads off of a couple of long bolts that are the same diameter and thread type as the originals. Slide the transmission into place. You may have to slightly turn the U-joint yoke to get the splines on the clutch shaft to mesh with those on the clutch disk. Remove the locator pins and tighten the bolts evenly, but never tighten the bolts until you are certain the transmission is properly meshed into the clutch disk.
Adding the Accessories
The final assembly of the engine with all its pumps and gadgets requires a little planning. Carefully examine everything before you start. Some items, such as fuel pumps, carburetors and fans can get bumped and damaged when reinstalling the engine, so you may want to wait until your engine is in the car before installing them. On the other hand, if these items are difficult to reach with the engine in the car, you may want them in place when you cautiously drop in the engine.
Here are a few pointers: When you attach the fuel pump, smear a little grease on the actuating lever, then make sure it is properly engaged on the camshaft. On some engines, the lever on the pump goes over the cam, and on others it goes under it. Check a shop manual to be certain of your application.
Always install a new thermostat of the correct temperature range when you rebuild an engine. New thermostats are inexpensive, and old ones can cause major problems if they malfunction. When installing the thermostat in the block, make sure it is oriented correctly. (This is very important on some cars.) Your shop manual generally will tell you how to install it and sometimes orientation instructions are stamped or printed on the thermostat. Use silicone sealer on both sides of the gaskets when installing the water pump. Let the sealer get tacky before attaching the pump. Don’t use any sealer on the gasket at the base of the carburetor when you install it because the atomized gas and air mixture passing through the carburetor will not leak out and the manifold heat could cause the sealer to burn.
When you attach the generator or alternator remember the belt only needs to be tight enough to prevent slipping. You should be able to deflect it between 3/4-inch and 1-inch in either direction with your fingers. If the belt is too tight it may snap and even if it doesn’t it can put unacceptable side loads on the bearings in the generator and water pump. It is usually easier to install the distributor after the engine is installed so do that later.
Setting It In
Because of its weight and size, installing an engine in a car can he dangerous. In addition the engine and car body can be damaged if the job is not handled with care. So by all means move the engine slowly and get an assistant to help you stabilize and maneuver it. Use a cherry-picker hoist or properly constructed chainfall hoist and a chain made of at least 3/16 inch welded links and at least 3 feet long. Never use your garage beams for support; they aren’t strong enough. In our case, the engine was on an engine stand and we began by loosening a head bolt at the right front side of the engine and one at the left rear, slipping a link of the lifting chain over each of the loosened bolts and tightening the bolts. (See the October 95 issue for tips on installing and handling the chain.) Slowly lower the engine or engine/transmission combination into your car. Attach the back motor mounts loosely then position the engine and attach the front mounts.
When you are sure everything is aligned properly tighten the mounts securely.
Reattach the drive shaft at the universal joint. Hook up the clutch linkage if your car is equipped with a standard transmission then adjust it to between 3/4-inch and 1-inch of free pedal travel before it starts to engage. Smear a light film of sealing shellac on the insides of the radiator hoses and slip them into place. Snug up their clamps just enough to prevent leaks and dont over-tighten them as that could damage the hoses. Fill the cooling system with the proper water-to-coolant mixture (check the manual for your particular car) and fill the crankcase with oil. (10-30 weight detergent oil is ideal for our little Chevy six as well as most other automotive engines, but check your shop manual to be sure your car doesn’t have other requirements.)
Don’t be too quick to attach the fuel line from the gas tank to the fuel pump. First connect the wiring to the battery, starter, coil, generator, and voltage regulator. Polarize the generator by touching a wire from the battery terminal on the starter to the armature terminal on the generator. Otherwise over time you’ll burn the points in the voltage regulator.
With the spark plugs removed, crank the engine while holding your thumb over the number one spark plug hole. Stop when you feel a sudden blast of air. Insert the distributor with its rotor pointing toward the terminal for the number one cylinder. You may have to rotate the rotor slightly to get the distributor tab to drop into place on the oil pump shaft. By making sure the number one cylinder is in the firing position then installing the distributor as described above you avoid the possibility of installing your distributor 180 degrees out from its proper orientation which is possible to do on many engines. Remove the rotor from the distributor, and with the spark plugs still out and the fuel line from the tank still disconnected from the fuel pump, crank the engine until a little pressure shows on the oil pressure gauge. Replace the ignition rotor, install new, correctly gapped plugs, then attach the fuel line.
The Big Moment
Before starting your new engine, carefully inspect everything. Did you forget oil? Coolant? Are all of your electrical connections correct, clean, and tight? When you are completely satisfied that things are in order, start the engine. Let it run at fast idle until thoroughly warmed up. While it is running, look for leaks, and keep an eye on the oil pressure and temperature gauges, if the car is so equipped, or watch the warning lights closely. Also listen for unusual sounds such as grinding, rattling and clunking. If you detect problems, shut the engine off immediately and remedy them.
Set the idle speed at the carburetor (475 rpm on our standard shift Chevy, 425 rpm if it is Powerglide equipped) with the help of a hand-held multimeter. Disconnect the vacuum advance at the carburetor. Hook it vacuum gauge to the vacuum advance fitting on the throttle body of the carb and adjust the mixture screw for maximum vacuum. You may have to go hack and forth between the mixture screw and RPM screw to get it just right.
If your engine is equipped with solid lifters set the tappets to the correct specifications. This is done using a wrench a screwdriver and feeler gauges while the engine is thoroughly warmed up and running. (See Feb. 1995 “Tappet Tuning.”) If your engine has hydraulic lifters, start the engine and back off each rocker adjustment until it clatters then tighten it the requisite number of turns according to your shop manual. (Chevy six rockers should be tightened one full turn but a Chevy V-8’s rockers should only be tightened 3/4-turn.)
When you are satisfied that all is well take the car out for a spin. Avoid hard accelerations for the first thousand miles and don’t drive at a steady speed for long distances because the engine won’t wear in evenly. Change the oil at 500 miles and again after another 1000 miles. Check the break-in oil for any signs of water, bits of metal or burning.
If you find no problems, congratulations! You have just completed one of the most challenging mechanical operations you can do on an old car!
Thanks for the info I have a 1940 chevy pickup with a 216, with low compression