If you are a pro engine builder, skip this article. If you have built upa few engines with some success, then read this lightly. If you've neverput an engine together with your own hands, this article should give youthe help you need.
COMPONENTS Some components make horsepower. Some components offerinsurance that the power will live. Be sure to spend your money wiselybecause insurance is expensive. Purchase only what you need. Let's sayyou know you're going to build a 350 Chevy engine. Get out the rule bookfor the track where you plan to race. It may specify the type of liftersthat can be used on the cam as well as the type of pistons (flat-top, 4eyebrow, etc.). The rules will probably spell out the type of cylinderhead to be used. You should know all of these things before buying anyparts. Once you've gathered the appropriate information, call up a camgrinder. Companies such as Comp and Crane have experienced staff thatwill point you in the right direction, making your engine fast andhelping you keep it legal. The cam is the heart of the engine. Selectingit first will allow you to match other components for the best power.
THE PARTS Now you're ready to get started. All of the parts for yourengine are laid out neatly, but the block must be cleaned. First, besure to keep all the main bearing caps in order. They should have anumber on them, but check to be sure. Since the block will need to bebored to fit your new pistons, be sure to have a machine shop clean itand check it for cracks before it is bored. The cleaning process willrequire the removal of the cam bearings. At the same time, take alongthe old pistons, new pistons, and rods. The wristpins are press-fittedin the rod. The machine shop can press the old ones off and install thenew pistons on the rods.
Here is where you can start spending money. Themachine shop will be able to align-hone the main bearing bores. Thecylinders can be bored with torque plates in place. The block can bedecked square with the crank and also flat. These are good things to do,as they unleash a little power and provide some insurance. But in yourStreet Stock engine, these things may not be necessary. If the enginewere in running condition and you paid a little attention to the piecesas you took them apart, the aforementioned steps should be easier. Ifthe main bearings on the crank were worn but not worn to one side, thenthe main bores should be straight enough. How straight is straightenough? How much do you want to spend? The engine ran a lot of miles theway it is now.
Be sure to inspect the rods carefully. After removing thebearings, look inside the bore on the big end. You should see somecrosshatch marks and the imprint of the brand of bearings used. If thesemarks are not present, and especially if there are radial marksindicating a bearing has been spun, then the rod needs reconditioning.
At this point, you will begin making decisions about insurance. The rodbolts hold up well in stock engines, but they become a failure point aspower levels rise. If the rpm level is held to 6,500 and horsepower isaround 350 (stock heads, good cam, four-barrel carb, and headers), thestock bolts hold up fairly well with good torquing procedures. However,a set of ARP rod bolts that are installed before the rods arereconditioned can be a real asset to bottom- end life.
The main bearing bores are...
The main bearing bores are checked for size. This is done after thebearings are removed and the caps are re-torqued.
Connecting rods take a lot...
Connecting rods take a lot of abuse. Good bolts such as ARP should beinstalled. The rod should be resized after changing bolts.
Take a close look at the crankshaft. Its journals should be smooth, without anydiscernable grooves. If this is the case, you should have the machineshop measure the journals for roundness. If they are smooth and not outof round by more than one-half of one-thousandth of an inch, you shouldbe OK. Remember we are building a low-compression, low-rpm engine, not aNextel Cup engine. But again, if you want insurance against failure,then have the crank ground and polished.
Now turn your attention to the cylinder heads. Again, consult your rule book to determine which onesare legal. You might also ask some local racers. The heads you chooseshould be cleaned and checked for cracks at the machine shop. Mostlikely your heads will need a valve job. If the rules and yourpocketbook allow, over-sized valves are nice but not absolutelynecessary. The head-mating surface should be inspected and checked witha good straight edge to see that it is flat. It's always a good idea tomill the surface to get more compression. Also, the machine shop caninstall the valves and springs if you don't have the tools at home.
ASSEMBLY Now you have all the parts in your shop. The next step is toclean all the parts again, even if they were cleaned before. With theblock bolted to an engine stand, turn it upside down so that the mainbearings are up. With the main caps laid to one side, clean the bearingbores with a brand of brake cleaner that does not burn. I use papertowels for cleaning during assembly. Be careful not to leave paperfibers scattered in the engine. Once the bearing bores in the block areclean, install the bearings. For years the standard race bearing hasbeen the Clevite 77 bearing used here. If your set has a groove in onehalf, it should be installed in the block. Do not touch the bearingsurface with anything, including your fingers. Handle the bearing at theedges. To be sure you have the right bearings for the crank and rods,buy a package of Plastigage. It comes with instructions. Plastigage willbe fine for checking. Having a good set of inside and outsidemicrometers handy would be better. What you want to do is verify thebearing clearance. Once the bearings are installed, apply a small amountof assembly lube of your choice. I like Lubriplate white lithium greasein a tube.
The rear seal may need to be installed before the crank,depending on the engine. Now, carefully lower the crank into place. Donot rotate the crank until all the main caps are in place and torqueddown. You must lubricate the main cap bolt threads and under the headwith oil before installation. Get a spec book and follow the torquerecommendations closely. When torquing an assembly, always work inseveral steps and from the center out.
Piston/rod installation requires a bit of work. Turn the block so that one cylinder bank is parallel withthe floor. First it is always wise to check the ring gap. I used PerfectCircle rings that were not file fit, which means they didn't need to befiled to the correct clearance, and the gaps proved to be right. Followthe manufacturer's directions for ring placement.
Remove the rod cap and clean the rod and cap bores with brake cleaner. Install the bearing inboth and lube lightly. Then turn the crank so that one journal is atbottom dead center. Now, from your local hardware store, get a piece ofclear vinyl tubing 36 inches in length that fits snug over the rodbolts. Double up the tubing and place it around the crank journal,sliding it out of the cylinder bore. Each end must slide onto a rodbolt. The tubing prevents the rod bolt from nicking the crank as thepiston is installed.
The head mating surface should...
The head mating surface should be inspected and checked with a good straight edge for flatness. If the head has bowed or flexed, it will need to be milled for flatness so you'll get a good seal on all cylinders. Milling the head also gives you an increase in compression ratio for some extra power.
The endplay of the crankshaft...
The endplay of the crankshaft is checked--a step that is oftenoverlooked.
This is a rod being resized...
This is a rod being resized on the big end. It is passed over anexpanding hone to achieve the correct fit.
Next you will need a ring compressor. Speedway Motors has a nice one-piece model that is adjustable. Liberally oil theinside of the ring compressor. A wooden hammer handle is a nice tappingtool to push the piston into the bore. Be sure to keep the ringcompressor tight against the block during this operation. If the pistoncomes to an abrupt stop, do not continue, because a piston ring has morethan likely slipped out of the compressor. Remove the piston and reset the compressor.
Once the piston is in the bore and the rod has been guided onto the crank, install the cap. Again, don't rotate the crankuntil the cap has been tightened. The reason for not rotating the crankis that you don't want the lube to spin into the space between the rodand the cap. This space should remain clean and dry. Once all rods arein place and torqued, it is time to install the oil pump. Care must betaken on Chevys to use the correct oil pump attachment bolt. The wrongbolt can do bad things to the rear main bearing. From engine to engine,you might find some differences, but on the small-block Chevy and thesmall-block Ford, the front timing cover is installed before the oilpan.
BACK TO THE CAM Get out that beautiful cam you selected and gaze at itfor a moment. Lather it up with assembly lube or whatever lube your camgrinder recommends. Too much will be just about right. Slide the cam incarefully, trying not to nick the cam bearings. A long bolt screwed intothe front of the cam makes a good handle.
It's now time for the timingchain. The stock chain works amazingly well in these engines.Aftermarket timing-chain sets offer several keyways for changing the camadvance. This is of little use unless you are experienced in the effectsof changes in cam timing. Save this part for your next engine. Degreeingthe cam is a time-honored procedure in racing engines. In this case wedid not align-hone the main bearing bores. Thus the distance from thecrank to the cam did not change. So for your first engine, leave thefancy stuff alone. On the V-8 Chevy there is a dot on the cam gear andthe crank gear. These two dots must line up at the point where they aretogether. Being one tooth off either way will not work. After the timingchain set is installed, remember to torque the cam bolts; the frontcover can now be installed.
Place something about 5/16 inch thick acrossthe pickup of the oil pump. Now, as a trial run, fit the pan with nogaskets. If the 5/16-inch spacer barely touches the pan, you should feelit rock slightly. If it does not touch, then try a 7/16-inch spacer.This spacer should touch the pan. If it does not touch, then remove thepan and make an adjustment to the pickup or the pan. Also check for anydents in the pan. For best engine oiling, the pickup-to-pan clearanceshould be between 5/16 and 7/16 inch without the pan gasket. Ready toinstall the oil pan? Not quite. Most used oil pans have had the boltsover-tightened. When this happens, thin metal dimples and leaks canoccur between the bolts. Using a piece of wood to spread the impact, tapthese dimples gently with a hammer. You want the gasket surface as flatas possible. Don't overdo it.
Now clean the pan once again. The pan gasket needs no sealer. The rubber seals at each end of the pan need asmall dab of silicone sealer at each end where they meet the gasket.
A word of caution about using silicone sealers is in order. If some isgood, then that's enough. Gaskets are designed to work in their place.Sometimes a smear of silicone around a water passage is OK. A dab at agasket joint is OK. Silicone is often used in place of a gasket at theends of the intake manifold on a Chevy V-8. It is OK to do all of thesethings if they are not overdone. I cringe when I see silicone hangingout of gaskets on valve covers and oil pans. When silicone squeezes outof an engine, it also squeezes into an engine. The silicone inside canget loose, and it doesn't dissolve in the engine. Instead, it stops upthe oil pickup screen, and this dissolves the bearings, among otherthings. I have seen this happen more than a few times--one time with myown engine. Learn the easy way or learn the hard way--just learn.
In Part 2 we'll spend some time prepping the cylinder heads. Oncethey're installed, we will move on to the valvetrain. We will alsoinstall the intake manifold, the distributor, and even the water pumpwith its pulleys.
The bore of the rod is checked...
The bore of the rod is checked after resizing.
The main cap bolts must be...
The main cap bolts must be tightened to the correct torque once thecrank has been installed. Do this in stages, and work fromthe center of the engine out.