Question about checking compression
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Question about checking compression
I am working on this 390 that I recently obtained that has been sitting a while. I am just cleaning it up, gaskets, etc. I want to check the compression but want to do it before I put it in the truck.
My question is: Is it possible to get a compression reading cranking the motor with a breakover on the crank bolt. I am not concerned so much with the actual compression but rather the consisitency of the compression between cylinders. If I have to I will take it off the engine stand and rig it up with the starter and check it that way. I have tested compression many times on different motors but they have always been in the vehicle, never done it by hand. Wanted you get your opinions.
Thanks
HD
My question is: Is it possible to get a compression reading cranking the motor with a breakover on the crank bolt. I am not concerned so much with the actual compression but rather the consisitency of the compression between cylinders. If I have to I will take it off the engine stand and rig it up with the starter and check it that way. I have tested compression many times on different motors but they have always been in the vehicle, never done it by hand. Wanted you get your opinions.
Thanks
HD
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From: lino lakes, mn
you could do a leakdown test if you've got an air compressor and ascrew in spark plug adapter for your compression gauge easiest way would be to pop the valve covers remove the rocker arm shafts then put air in each cylinder listen for leakage at the intake,exhaust, and valve covers this will aleast tell you if you have bad valves or rings
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Thanks guys. I guess I will go ahead and rig it up with a starter. Figured I would have to, I was just hoping for the easy way out. I should know better though. Very seldom is the easy way adequate.
Since I am going to go ahead and do it that way, what kind of compression should I be looking for. I think the motor is pretty much stock other than the Eddie Performer 390 intake.
Do most parts stores have what it takes to do the leak down tes? I might just go that route.
Thanks again to you guys who are willing to help the rest of us out
HD
Since I am going to go ahead and do it that way, what kind of compression should I be looking for. I think the motor is pretty much stock other than the Eddie Performer 390 intake.
Do most parts stores have what it takes to do the leak down tes? I might just go that route.
Thanks again to you guys who are willing to help the rest of us out
HD
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Joined: Feb 2004
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Hawg, Summit has an all right leakdown tester , for about $66. Depending on your budget and what else you might need/want. That is probably the easiest route , unless you can rent or pick one up cheaper locally. Doing or attempting compression by hand doesn't work- tried it once. JR
