Compression test, Is there a low cost Way?
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Joined: Jun 2002
Posts: 40
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From: Southern Indiana
Compression test, Is there a low cost Way?
I have a 1983 12A engine that misses at any steady rate of rpm. The fuel system has been refurbished as in cleaned, tank cleaned and coated, carb dissembled to reveal an incredible amount of corrosion, replaced with an earlier mdl carb that looked OK but may not be. The fuel inlet plumbing was dissembled and found to be clean, no corrosion as opposed to the original carb.
This Rx7 was bought from a used car dealer for $300.00 salvage value and needs lots of work. My first priority is to get the engine running properly then go to the other things.
My thought is to try to verify the condition of each component beginning with the basic engine.
How can I test the engine for interior condition without dissembling it? Most usually a compression test will tell the tail in piston engines. The dealer wants $100.00 dollars to run a test. I cnannot get it there other than on a trailer. Is there any way I can do this myself and get a clue as to the internal condition??
The engine has lots of power at maximum throttle, does not back fire upon release of throttle. Simply will not run at a steady cruise rpm or any other rpm level yet idles fine. There is a hose that may be missing on the right side of the carb. I cnanot find a reference to this in the Haynes manual. There is a valve located above and a little aft of the base carb right rear mounting bolt which looks as if there should be a hose running from this to the air clearner housing. ?? Also there is a hose connected to nothing running from what I think is the cold weather start reservoir to the left side of the carb. Where does this connect to the carb?? All the polution valves are in place as I want it to eventually be a daily driver.
Best regards,
THC
This Rx7 was bought from a used car dealer for $300.00 salvage value and needs lots of work. My first priority is to get the engine running properly then go to the other things.
My thought is to try to verify the condition of each component beginning with the basic engine.
How can I test the engine for interior condition without dissembling it? Most usually a compression test will tell the tail in piston engines. The dealer wants $100.00 dollars to run a test. I cnannot get it there other than on a trailer. Is there any way I can do this myself and get a clue as to the internal condition??
The engine has lots of power at maximum throttle, does not back fire upon release of throttle. Simply will not run at a steady cruise rpm or any other rpm level yet idles fine. There is a hose that may be missing on the right side of the carb. I cnanot find a reference to this in the Haynes manual. There is a valve located above and a little aft of the base carb right rear mounting bolt which looks as if there should be a hose running from this to the air clearner housing. ?? Also there is a hose connected to nothing running from what I think is the cold weather start reservoir to the left side of the carb. Where does this connect to the carb?? All the polution valves are in place as I want it to eventually be a daily driver.
Best regards,
THC
Joined: Oct 2001
Posts: 6,444
Likes: 0
From: Fort Branch, Indiana
Use a regualr compression tester, remove the little valve that holds pressure. Have someone crank it over. Take a video recording device and film the bounces of the needle. Play back in slow mo and watch for 3 steady even bounces somewhere around 80-110 PSI.
Good luck..
Good luck..
Joined: Oct 2001
Posts: 6,444
Likes: 0
From: Fort Branch, Indiana
Originally posted by peejay
If it starts, the compression is good.
If it starts, the compression is good.
Id had like 85 ... ... and 105 95 85
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