compression ratio questions

[dj_joker_2002]

I started with a 1986 Iroc 5.0 engine known as a LB9 I sold the TPI stuff
overhauled the short block assembly with the stock pistons simply because the engine had approx 60,000 miles on it. I had to replace the stock crank so I bought a reconditioned one. I sold the stock cyl heads and bought a set of L31 vortec heads and had them reconditioned and shaved 12,000 to keep my compression up as the stock heads had smaller combustion chambers then the L31's do. Now my questions: how do I get an idea of where my compression is with the shaved vortecs? what info do I need ?

[astronut74]

You need to get the heads cc'd. You find that by using a buret to fill the combustion chamber with a light oil. To get a glass buret can be expensive, but you can find them here http://www.goodson.com/store/template/i ... 040137fbc3
You could also get a plastic one, but I here they aren't as accurate... Although your machine shop should have the equipment to do that I would think.

[astronut74]

Sorry, you could get lost looking for the buret in that first link I posted... Here's a link for the glass buret: http://www.goodson.com/store/template/p ... 040137fbc3

[dj_joker_2002]

Well I did some research and found this out: the stock heads had a combustion chamber volume of 58 cc & the vortecs prior to the shave of 12,000 had a combustion chamber volume of 64 cc so by those calculations
my compression should be pretty close to what was stock. However I don't have a clue as to what the thickness of the gaskets was and how that affected the compression ratio. Next Spring I may pull the top off the engine and redo the gaskets with thinner gaskets.