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360 Compression Testing

I've just compression test

I've just compression tested my 360 and all results ranged from 75-90 on each cylinder. This is the first time for me and I can't find any guidelines online for what the compression should be. Can anyone help me out please.
 
"That sounds a bit low, but it

"That sounds a bit low, but it might just be your tester. Consistency between cylinders is more important, and yours look okay.

Jeff"
 
wouldnt the results change if

wouldnt the results change if compression was tested with a warm motor? doesnt it only matter what the compression is at operating temp as the rings tend to expand with heat? curious about this myself....
 
"The problem with reading gage

"The problem with reading gages is you never know what the true readings are. Just 'cause your speedometer says your car is doing 60 mph, doesn't mean it is.

Compression testers have some additional problems, such as volume inside the hose. A good tester keeps this volume to a minimum; cheapos don't. Then there's that little tire valve; it can leak--and we're talking about a really small volume of air here--screwing up the readings.

So don't put a lot of stock in the amplitude of the readings (unless, of course, they are super low).

Finally, on your temperature variation question: Sometimes it can cause a difference, sometimes not. Opening the throttle wide open is another variable...sometimes! Go figure.

Jeff"
 
"And since I did the compressi

"And since I did the compression test incorrectly, that would make the results off as well. I only turned the engine until the guage jumped once and wrote down that number. Since then, have learned that I should crank until the gauge needle jumps 3 or 4 times. These are the new results.

125-135
120-135
115-120
100-115

Thank you for your input on the last numbers Jeff. Could you look at these and post your thoughts please. The range is 100-135. Is 35 psi a big variance between cylinders?"
 
Thanks Jeff. I boat all year

Thanks Jeff. I boat all year long down here on North Padre Island TX. Not having to winterize is great. Thanks again for all your help.
 
"David,
I make an annual trip


"David,
I make an annual trip to South Padre each year in April. Next year, I'm calling you for a boat tour!"
 
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