Editing Basics of a build

BLOCK DECK HEIGHT: The measurement from the centerline of the main bearing bore to the flat part of the block deck where the heads bolt on. Blueprint measurement of a Gen I small block Chevy is 9.025" and a factory "stack" of parts will measure 9.000", leaving a piston deck height of 0.025". PISTON DECK HEIGHT: The measurement from the crown of the piston to the flat part of the block deck where the heads bolt on with the piston at top dead center. PISTON COMPRESSION HEIGHT: The measurement from the centerline of the wrist pin to the crown of the piston. Blueprint calls for 1.560" on a Chevy Gen I small block motor. As has been discussed above, there are rebuilder pistons which may measure 1.550" or 1.540", which goes the wrong way for a hot rodder looking to engineer a proper squish/quench into his motor. Lately I have noticed that Skip White is offering a special piston design that features a 1.575" piston deck height. Keith Black pistons also offer an increased piston compression height, but not as tall as the Skip White offerings. I would like to shake Skip's hand for addressing this problem and offering a solution. Thank you Skip. I would also like to see pistons available with an even taller piston compression height, like 1.585"or 1.590", so that a builder could whittle on both the piston and the block and make a zero deck without cutting the block decks so much. But that will probably never happen, just too much wishful thinking on my part. SQUISH/QUENCH: The measurement from the crown of the piston to the underside of the cylinder head with the head gasket in place and with the piston at top dead center. Most builders will agree that a measurement of 0.035" to 0.045" will be the most effective in preventing detonation. In order to work, the piston crown must have a flat plateau opposite the combustion chamber which matches up with the flat part of the cylinder head opposite the chamber. As the piston ascends in the bore, these two come together, squishing out the fuel/air mixture from that area and blowing it over into the combustion chamber, thus homogenizing the mixture there through the turbulence created. This breaks up larger droplets of fuel, allowing a more complete combustion process and thus developing more horsepower as well as suppressing detonation. Famed engine builder David Vizard has stated that the tighter he runs the squish, the more horsepower the motor makes, up to the point of imprinting the piston part number on the underside of the cylinder head. Quench refers to the act of transferring heat from the piston to the underside of the cylinder head so that the coolant can carry heat to the radiator. Be very careful in your choice of piston design because some pistons are manufactured with a thin ring around the perimeter of the crown that have insufficient area to engage the underside of the head to create squish. Some of the best are the D-cup designs offered by Keith Black pistons. They feature a very generous flat pad. ALUMINUM HEADS: When using iron heads, there is no dissimilar growth between the block and the heads, they're both made of the same material, growth and shrinkage are the same through heat cycles. But when using aluminum heads on and iron block, there is dissimilar growth and the head moves on the head gasket, causing wearing away, or fretting, of the aluminum at the clamping surfaces. If you look into this, you will see that every manufacturer of aluminum heads recommends a thick composition head gasket to prevent this fretting condition. The thicker gasket gives some and keeps the head material intact. Problem is, with a stock 0.025" piston deck height and a ~0.040" composition gasket, the squish/quench is thrown for a loop at ~0.065", so that there is no help from a tight (0.035" to 0.045") squish/quench. This is where you need either a taller piston, like the one mentioned from Skip White, or you need to take a cut on the block to bring it closer to "ZERO DECK" so that you can run at least a 0.028" composition gasket and more correctly, a 0.039" to 0.041" gasket, such as the Fel-Pro 1003 which is suggested by Airflow Research and others. Getting this part of the build right is just working the basics, but it is much misunderstood and disregarded by most amateur builders.

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