This is measured from the center of the crank to the top of the block on both sides, left bank and right bank. A quality machine shop like Pfaff Engines of Huntington Beach, California, will be able to check your deck height and machine the block according to where your requirements for clearances and compression need to be. Most, but not all of the Chevy Gen II one-piece rear main 350 blocks, come with a 9.025 deck height. Machining or zero decking the block is done by removing .025 off the block, making the deck height 9.000 inches total on both sides. Now this can be problematic or a blessing depending on the parts utilized. For example, some stroker kits will take into consideration that machining the block down is expensive and some people are not going to do it, so they might spec the pistons so that they are less than .025 in the hole.
Piston Compression Height
Many people confuse piston height with deck height. Piston compression height is a measurement taken from the center of the piston's wrist pin to the top of the piston. A 5.7 rod will have a larger piston compression height than a 6.0 rod with the same stroke crank. To figure out what piston compression height you need per your rod size, you need to calculate the following. First, divide the stroke 3.750 by 2 = 1.875; add this to the rod length + 5.70 = 7.575 minus the 9.0 deck height = 1.425 piston compression height, this is for the shorter rod. The 6.0 rod for a 383 is calculated in the same way: 3.750 divided by 2 = 1.875; add this to the rod length + 6.0 = 7.875 and minus the 9.0 deck height = 1.125 piston. Lunati uses a 0.005 taller piston that will put the deck height of the piston at 9.005 or +0.005 out of the hole if the block is zero decked or machined to 9.000. Now, if for some reason you decide to not machine the block, then the Lunati piston will be 0.020 in the hole.
Dish, flat, and domed are the three common types to choose from, but for the most part we are looking at the either dished or flat. Dished pistons are just that – dished to reduce compression and are measured in minuses (-18.6cc). Flat-top pistons are flat on top and increase compression and have valve reliefs on top. They can measure plus or minus, but most common are minus (-4.9cc). Domed pistons protrude into the combustion area of the head and are measured positive or plus (+12cc).