How do i figure out my compression?
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Junior Member
Joined: Jan 2003
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How do i figure out my compression?
When i bought my car i was told that it had a 1978 350 from a camaro that was rebuilt but it was just a stock rebuild and that would make it a 8.5:1 compression. I was told it was a 9:1 compression engine i just want to check and see what one of these is correct. Thanks
TGO Supporter
Joined: Aug 1999
Posts: 14,811
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From: Jackson County
for an accurate figure you'd need to know the dish/dome volumn, chamber volumn, head gasket thinkness, and the deck clearance, so if the engine is together best you can do is guess or estimate
Supreme Member
Joined: Sep 2001
Posts: 6,111
Likes: 53
From: Ontario, Canada
Car: 1988 Firebird S/E
Engine: 406Ci Vortec SBC
Transmission: TH-350/3500stall
Axle/Gears: 7.5" Auburn 4.10 Posi-Traction
Go to www.download.com
You can download engine CR ver1.0
Nice compression ratio calc.
Next you can get an idea of what you have by getting the head casting number. You need to remove one of the valve covers
to see it.
go to www.mortec.com and find your head casting # in the listings.
While there are still unknown variables like piston dome volume
etc. If it turns out you have a cylinder head with smaller than stock chambers, (76cc) your cr will be higher than stock.
Hope this helps, some.
You can download engine CR ver1.0
Nice compression ratio calc.
Next you can get an idea of what you have by getting the head casting number. You need to remove one of the valve covers
to see it.
go to www.mortec.com and find your head casting # in the listings.
While there are still unknown variables like piston dome volume
etc. If it turns out you have a cylinder head with smaller than stock chambers, (76cc) your cr will be higher than stock.
Hope this helps, some.
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