I have a 355 that i bought off one of my friends. I was wondering if you recognize these numbers of the top of the pistons

H423NP .030
077-05-11-B

I just need to know what CC the dish is to calculate my static compression ratio.

 

Bore (in) 4.030 in.Bore (mm) 102.362mm

Piston Style Dish, with four valve reliefs
Piston Material Hypereutectic aluminum
Compression Distance (in) 1.540 in.
Piston Head Volume (cc) +10.00cc
Wrist Pin Style Press-fit
Pin Diameter (in) 0.928 in.
Piston Ring Thickness 5/64 in. x 5/64 in. x 3/16 in.

0.070 inch deep dish.

 

Those are SpeedPro / Sterling hypereutectics.

Note the compression distance: 1.54".

Stock is 1.56".

Those pistons have the usual "rebuilder" extra .020" of deck clearance. Don't forget to include that in your "calculator". If there's not a place to enter it, add the .020" to the head gasket thickness you type in.

If you fail to take this into account, your "calculations" will show SIGNIFICANTLY higher numbers than what's REALLY in your engine, rendering them worthless.

Not much of a performance setup unfortunately.

 

Exactly what he said. If the block hasn't been decked the deck height will be right around 9.025, add the fact that the piston is never at a true 9" top of the hole but usually a .005 under it and the .020 lower comp. height that already gives you a quench height of at least .050 or so with no head gasket. If you want to build a perf. motor out of it you need to do soemthing about at least those pistons since no gasket will be thin enough to give you any reasonable compressed thickness to work with here.

 

Thanks for all the reply's.

The block has never been decked an the engine has 64cc gm heads with a .041 head gasket......so with the 10cc dish an the .020 off the compression height
it was running 8.9-1 with a comp 292h

http://www.rbracing-rsr.com/compstaticcalc.html