Modern Engine Blueprinting Techniques. Mike Mavrigian

engine oil, connect the intermediate shaft to the pump, and turn the shaft by hand. Oil should exit the outlet port of the pump. Finally, install the pump.

      Before installing the distributor, use a pre-oiling adapter to engage the oil pump. With the valve covers off, turn the adapter driveshaft with an electric drill. Keep turning until you see oil at each rocker location. This may take a few minutes, so be patient. Install a temporary oil pressure gauge at the block’s oil pressure gauge port to verify that you’ve built sufficient pressure. At this point you can install the valve covers and distributor, and you’re ready to fire.

      Gerotor Oil Pumps

      If the engine has a gerotor-style, crankshaft-driven oil pump, you can’t drive the pump in order to pre-oil the engine. You need a remote oil pressure canister, which is a pressure tank with an internal bladder. Melling’s pressure canister prelube kit (MPL-101), for example, holds 4 quarts of engine oil.

      First, add oil (depending on the model, this may take 4 quarts or more). Charge the tank with compressed air. Connect the outlet hose to a fitting that threads into a main oil galley port (located on the driver’s side of the block, toward the front, just behind the timing cover). LS blocks have a 16-mm x 1.5 threaded hole.

      Connect the canister hose to the appropriate fitting (this should be supplied with the canister) and open the canister valve. Pressurized oil is then pushed throughout the engine’s oil passages.

      Gear-Type Oil Pumps

      In a gear-type oil pump, oil pump gear length affects volume. The larger (longer) the gears, the more volume. Pressure regulator springs (which can easily be changed) allow you to adjust when the pump’s bypass valve opens (valve opens earlier, lower pressure; valve opens later, higher pressure). For example, Melling’s small-block Chevy M55 standard volume/standard pressure pump has 1.200-inch-long gears and is regulated at 55 to 60 psi. The M55A standard volume/high-pressure pump has 1.200-inch-long gears and is regulated at 75-80 psi. The M55HB high-volume pump, which has a 1.500-inch-long gearset, is rated at 70 psi.

      If pump pressure is too high and the engine has tight bearing clearances, the pressure rises until it finds an escape path. A pressure relief valve in the pump releases pressure. Otherwise, pressure can rise to the point of bursting an oil filter. Certain engines can benefit from a high-volume pump, such as old Ford big-blocks that have cam-bearing priority oiling, which tend to starve the mains.

CHAPTER 5

       ENGINE MATH

      This chapter provides information that will aid in understanding essential dimensions and volumes that are considered when planning and executing an engine build.

Bore and Stroke

      In general, a long-stroke engine (an engine with a relatively long stroke in relation to bore diameter) revs slower but produces more torque at lower RPM. A short-stroke engine (short stroke in relation to a larger bore diameter) revs higher, and produces peak power at a higher RPM range.

      A crankshaft’s stroke dimension is the total stroke of the crankshaft. This is measured from the rod pin’s BDC to TDC positions. When selecting a crankshaft, connecting rod, and piston combination, you use one half of the crankshaft’s published stroke dimension in your decision making. The distance from the centerline of the crank rod pin at TDC, plus rod length, plus piston compression distance is the length that must fit within the block’s available deck height dimension (the distance from the main bore centerline to the block’s cylinder head deck surface).

      As an example, if you install a 4.000-inch-stroke crankshaft, the crank and connecting rods have a 6.125-inch length and the pistons have a compression distance of 1.115 inch. The block has been square-decked to a deck height of 9.234 inches and achieves 403.13 ci with 4.005-inch cylinder bores. With that stroke/rod/piston combination, the pistons protrude above the decks by .006 inch, which is more than compensated for by using cylinder head gaskets with a crushed thickness of about .045 inch.

      The stroke package must fit within the block, so you must always consider the block’s deck height. LS factory blocks, as an example, are notorious for having unequal deck heights (high/low side-to-side and/or front-to-rear). So before choosing your stroker combination it’s wise to first have the block decks surfaced in order to establish equal deck distance from the crank centerline. You can probably fudge this and assume that the decks are okay, but if you want absolute precision, correct (or at least carefully measure) the block deck height at all four corners (right-front, right-rear, left-front, and left-rear) before spending money on rods and pistons for a stroker combination.

       The stroke package must fit within the confines of the block, so you must always consider the block’s deck height. Deck height is the distance from the main bore centerline to the block’s cylinder head deck surface. Most OEM blocks (because of a wider range of manufacturing tolerances) have uneven block decks, especially deck height and deck taper. High-quality aftermarket blocks will commonly provide extra deck height to allow you to cut the decks to exactly suit your piston-to-deck clearance.

       Even today’s OEM LS factory blocks, to cite but one example, are notorious for having unequal deck heights (high/low, side to side, and/or front to rear), so it’s wise to first have the block’s decks surfaced in order to establish equal deck distance from the crank centerline before choosing your stroker combination. You can probably fudge this and assume that the decks are okay, but if you want absolute precision, correct (or at least carefully measure) block deck height at all four corners (right front, right rear, left front, left rear) before spending money on rods and pistons for a stroker combination.

       Pictured here is a forged 4.000-inch stroker crankshaft from Lunati. This crank was coupled with 6.125-inch-long connecting rods and pistons with a compression distance of 1.115 inches in a factory LS2 block. This block was square-decked to a deck height of 9.234 inches and resulted in 403.13 ci with 4.005-inch cylinder bores. With this stroke/rod/piston/block combination, the pistons protrude above the decks by 0.006 inches. Using cylinder head gaskets with a crushed thickness of approximately 0.045 inches more