When it comes to hot rods, bench racing never seems to stray very far from engines. Power is where hot rodding will always be. When it comes right down to it, the only way to learn how to build engines and make power is to roll up your sleeves and do it. That's what this story is about. It's aimed at the first-time hot rodder who wants to take on that challenge of assembling his (or her) first engine.
Perhaps the most important tool that any first-time engine builder must have in abundance is time. Inexperienced engine builders tend to be in a hurry. Unfortunately, this is when shortcuts become too tempting. Save yourself the grief and do it right the first time. In this buildup, we'll outline the correct way to machine and assemble a small-block Chevy.
An actual step-by-step engine buildup is a lengthy process, so we've had to take a few liberties with the procedure. We'll cover the main items, but all the little things must be addressed if the engine is to be properly assembled. We'd suggest reading several buildup stories and investing in HP Books' How To Build Your Small-Block Chevy, which goes into far more detail. The more information you have before you start, the fewer problems you'll have along the way.
The best way to ensure the engine is assembled properly is to test-fit the short-block before the final assembly. This takes more time and even more patience, but it is the best way to build an engine. Professional engine builders often test-fit an engine several times before all the clearances and dimensions are built to their satisfaction. While this usually involves expensive race engines, the same care and attention to detail will ensure your everyday street engine will be both powerful and durable.
Test-fitting centers mainly around the short-block to ensure the proper clearances. Piston-to-wall, rod and main bearing, and rod side clearance along with crank end play are a few of the critical dimensions that must be correct if your engine is to have a chance of survival. This means using precision instruments like micrometers and dial indicators. If you don't have any experience using these types of tools, you will either need to learn or have someone you trust measure your pieces for you. If you've never assembled an engine before, it might be wise to have someone with experience inspect your work. Often, that extra pair of eyes will catch a mistake before it's too late.
This brings up another point that is critical for engine builders to understand. Regardless of whether the machine work is done by a local shop or you purchase a mail-order engine kit, it is the ultimate responsibility of the engine builder to check all the clearances to ensure everything is in order. One slightly oversize rod journal combined with an undersize big end of a rod can take a normal 0.0020-inch rod-bearing clearance down to under 0.001 inch, and that's guaranteed to fail. The only way to know is to measure each and every clearance.
Plastigage can be used to check your work, but most professional engine builders don't recommend using Plastigage as the only source of information on bearing clearance. The right way to determine bearing clearances is to mic the main and rod journals, then install bearings in each of the rod and main bores and measure the vertical inside diameter of the bearing. Subtract the journal outside diameter from the bearing inside diameter and the net result is the bearing clearance. It's a simple task, but this will take some time, so be patient.
All these recommendations are intended to help you assemble your engine correctly the very first time. By preassembling the engine, you will gain valuable knowledge and confidence to do the job correctly. Then when it comes time to assemble the engine for the final time, you'll be traveling through familiar territory.
