Compression Test
Thread Starter
Pro
Joined: Aug 2001
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From: Lake Lure NC
Compression Test
I need to do a compresson test to determine if my head gasket/rings are still OK. I am having an overheating problem and I thnk my head gasket is the problem. :mad What is the best compression tester to use and what is the range the compression should be at each pistion?
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
Re: Compression Test (mothersworry)
I got a nice one from Sears (so where else); it comes with instructions.
My GM Shop Manual says to give each cylinder 4 "puffs" and take the final reading. Further that each cylinder should come up close to the final reading on the 1st "puff".
My GM Shop Manual says to give each cylinder 4 "puffs" and take the final reading. Further that each cylinder should come up close to the final reading on the 1st "puff".
Le Mans Master
Joined: Aug 2001
Posts: 8,107
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From: California
St. Jude Donor '05-'06-'07-'08
Re: Compression Test (mothersworry)
I don't know what the pressure range would be in psi, but all the cylinders should be within ~10% of each other. (pretty sure)
Team Owner
Joined: May 2002
Posts: 24,337
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From: San Diego , CA Double Yellow DirtBags 1985..Z51..6-speed
Re: Compression Test (Knight Ryder)
I've heard about 140-160 psi for a stock LT1. I was up to 190 on some cylinders on my L98, but that's likely due to lots of carbon buildup.
Drifting
Joined: Feb 2000
Posts: 1,994
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From: Charleston, WV
Re: Compression Test (CentralCoaster)
The number of puffs varies according to who you talk to. I used to use 3 puffs years ago and a textbook I use for teaching says 5. It is correct , however that you should get a big first puff. A good strong engine will hit hard on the first. Too high is usually carbon buildup. If you find a low one do a leak down on that one to find where the loss is. Take out ALL the spark plugs when you do this and disable the ignition and fuel pump. They say to also block the throttle wide open too.
A good guage will screw into the cylinder as opposed to one that you would just hold in place .......... many REAL good guages have different hoses for different spark plug types. Others just have adapters.
Good luck with it :thumbs: :seeya
A good guage will screw into the cylinder as opposed to one that you would just hold in place .......... many REAL good guages have different hoses for different spark plug types. Others just have adapters.
Good luck with it :thumbs: :seeya
