what should the cranking compression be....

I have a STOCK 1977 chevy 454 from a pickup truck that I am wondering how many pounds of compression it should have if it was fresh/new? It has 8.25-1 compression ratio. I'm going to do a compression test on it but would like to know what a baseline would be. Thanks.....

 

The cranking compression of a 1954 Cadillac 331 with 8.25:1 compression ratio is listed at 150 lbs. minimum. I don't have any newer books.

 

I would have to look it up, but I wouldn't be surprised if it was between 120-140psi. Look more for how close all the cylinders are, instead of what the cranking compression should be.

The camshaft makes a huge difference on cranking compression, and tolerance stack usually puts those engines a half point or more lower.

 

http://www.wallaceracing.com/dynamic-cr.php

That should tell you what you want to know.