Although dynamic balancing is optional (extra cost) with all engine builders, it is a necessity to engine smoothness and longevity. It is manda-tory at MCE Engines, but Marvin takes it a step further with his own disciplined approach to dynamic balancing. He weighs everything before it goes to Automotive Balancing, then AB precision balances everything to Marvin's own specs.
Dynamic balancing happens for the same reason we balance tires-to remove shake and vibration. Centrifugal force is an ugly thing when spinning and reciprocating parts are not in perfect balance. All pistons, rings, and bearings must weigh the same. Engine oil must also figure into this equation. Pistons and rings must weigh exactly the same as crankshaft counterweights. They should dance around each other smoothly, with the precision of a Swiss watch.
With dynamic balancing, each piston is machined down to the same weight as the lightest piston. Rings and pistons are weighed together as individual assemblies. All rods must weigh the same as the lightest one. To get it all in balance, remove metal from the heavier parts to get them down to the same weight as the lightest part. The same can be said for the crankshaft.
Internally balanced engines can be balanced independently of the harmonic balancer and flywheel/flexplate. Externally balanced engines, like the small-block Ford and FE-Series 428 Cobra Jet big-block, call for including the harmonic balancer and flywheel/flexplate in the balancing process.
Assembly begins with cleaning...
Assembly begins with cleaning everything. Marvin works the oil galleys with lots of soap, water, and brushes. He uses rifle-cleaning brushes to make sure every trace of dirt and iron particles are gone. He also visually inspects everything closely. Does the passage look clean to your naked eye? Can you see all of the passage?
Because Blair is running a...
Because Blair is running a large-radius 4340 steel crank, it's necessary to use H-Series Clevite main and rod bearings. Notice Marvin has opened up the oil-galley passages to improve oil flow. Remember, crankshaft journals roll on a solid cushion of pressurized engine oil. Oil isn't just a lubricant; it is a coolant as well. He wants clearances that aren't too tight, which would restrict oil flow. The right measure of clearance and oil flow carries heat away from the bearings.
Once Marvin properly seats...
Once Marvin properly seats the main bearing halves in the block saddles, he gives them a dressing of his own assembly lube. Never use too much. Marvin supports doing a pressure prelube on your engine before firing to ensure plenty of lubrication at the bearings and on all moving parts.
Late-model small-block Fords...
Late-model small-block Fords utilize a one-piece rear main seal common from 1985-up. Although Fel-Pro doesn't suggest using a sealant around the circumference of this seal, Marvin recommends it. He runs a thin film of high-temp RTV silicone around the outside to ensure proper sealing.
With the mains lubed, Marvin...
With the mains lubed, Marvin is good to go with crank installation. He thoroughly checks main journal clearances, keeping them around .00220 inch with an average of .00224 inch. Rod bearing clearances run about the same at .0021 to .0022 inch, averaging .00218 inch. Endplay is .005 inch.
Before Marvin sets the main...
Before Marvin sets the main caps, he applies high-temp RTV silicone sealer between the No. 5 rear main cap index and block for additional sealing. This reduces the chance of engine oil leaking between the main cap and block.