3DFORMULA

iTrader: (4)

I'm disassembling the used 383 forged shortblock that I just purchased. After a through cleaning of the pistons I choose to put my digital slide caliper to one of them. Piston #7

Here is the results I have:

Piston ringland: 3.998"

Piston skirt: 4.028"

Cylinder bore top: 4.008"

I could use getting a different bore caliper to reach down further in the cylinder. The numbers look like the piston is tapered. And this is a .030 over motor but the top of the cylinder ain't measuring up. I really don't even know what to ask.

guppymech

iTrader: (7)

I'm not sure you can get a meaningful piston measurement in the ringland area. Pistons are measured 90 degrees to the piston pin. Forged pistons aren't symmetrical around their circumference.

BIGCAT7274

all pistons have some tapper to them. the top of the piston will a lot more heat than the skirt. for example i have some 4.125 bore stuff. 1/2" up from the bottom of the skirt measures 4.1210 the top of the piston measures 4.0840