compresion question

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Aug 20, 2005 | 01:44 PM

srsjuju

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Melting Slicks

Joined: Apr 2003

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From: Wood Dale Il.

compresion question

Does any one know the stock compression in a 85 vette
Not the compression ratio but what the compression test should show per cylinder

Thanks

Aug 20, 2005 | 01:49 PM

Morley

Drifting

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From: GA

Its not so much what the cylinder pressure is as much as all 8 should be very close to each other in pressure readings.
Figure around 110 psi for a healthy engine..anything below 90 and I'd start to worry.

Aug 20, 2005 | 01:57 PM

Corvette Kid

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From: Good health is merely the slowest possible rate at which one can die

St. Jude Donor '04-'05-'06-'07

Generally even w/ a maximum of + or - 10% variation. This along with no obvious wear problem symtoms indicates a reasonably healthy engine.
Oh and get some temperature in the engine before running the test.

Aug 20, 2005 | 11:04 PM

kopbet89c4

Safety Car

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From: Poop land

For me so far, I am about 150 psi +/- 5 psi on all cylinders. Leakdown test from the radiator looks also good. I'd pressurize the cooling system and see how long the system holds pressure. If it loses pressure, I'd be worried!

Aug 20, 2005 | 11:38 PM

CentralCoaster

Team Owner

Joined: May 2002

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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed

I tested at 185-195psi on my 85. As mentioned, there is no magic number. Depends on lots of things, starter condition, battery condition, engine temp....

Also, check the guage while you crank, see how many turns it takes to get to full pressure.