S&S 113 compression PSI

[TonyJ]

OK, I sent my 113 heads out to Robbie McCay, he did a port job and put in new valves. Took .030 off the deck, and Im running ..030 head gaskets. (Stock was .048 and had, according to S&S 10.1 compression.) 0 piston deck height.

Im running the S&S640 cam, and I figured that with taking .030 off the heads and .018 out in gasket, my CR should be about 10.8.

When I do a ccp test I get 170-175PSI, is this about right?

Thanks

[gsxrboy96]

Originally Posted by TonyJ

OK, I sent my 113 heads out to Robbie McCay, he did a port job and put in new valves. Took .030 off the deck, and Im running ..030 head gaskets. (Stock was .048 and had, according to S&S 10.1 compression.) 0 piston deck height.

Im running the S&S640 cam, and I figured that with taking .030 off the heads and .018 out in gasket, my CR should be about 10.8.

When I do a ccp test I get 170-175PSI, is this about right?

Thanks

I cant directly answer your question, but i will tell you this, psi in the cylinder doesnt directly correlate to compression ration, simply because of camshaft profiles, duration, overlap and all that stuff, my buddys 12.5 to 1 468 only has 200 psi cranking compression, because of the huge overlap. hope that helps.

[skidmark316]

When I do a ccp test I get 170-175PSI, is this about right?

A 640 in a 113 with a mechanical cr of 10.8 would be about 182-183 psi at sea level. You're probably at about 800ft above sea level, so that would be around 178-179 psi. So if your gauge is accurate, 173 psi is about 10.6 mechanical.

[TonyJ]

Thanks for the info guys. I will get my hands on a better gauge and recheck, but this atleasts lets me know its not too far off, and now I can sleep again at night. Really.

Thanks again.