I had a bad miss shift the other day and the engine reved to god knows how high. Everyone said that I may have bent my valves and I should check the compression. So I did and it came back 175, 165, 175, 180 psi. My helms gives a minimum of 135psi with a maximum variation of 28 psi. I am assuming that this means that it can be higher. And that the maximum variation is the bigest variation between cylenders and not the highest the compression can be (135+28 163psi). and that my readings are good and I bent no vavles is this correct???

 

Retake your test and see what you get.

Man thing you want to worry about is numbers dropping out of the pattern by 10.... like your number 2 is doing.

I never heard of you should have 135psi.... i would think thats way to low. All ive seen and believe are good is a avg. of 180psi. Do it again and see what you get.

 

I have never done a compression test before # 2 was kind of weird and made a loud chirp. It kind of freaked me out so I don't think I cranked it as much as the rest. I will do it again this time I will be sure to crank it the same is there any specific # of cranks???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bgoetz &raquo;</TD></TR><TR><TD CLASS="quote">I had a bad miss shift the other day and the engine reved to god knows how high. Everyone said that I may have bent my valves and I should check the compression. So I did and it came back 175, 165, 175, 180 psi. My helms gives a minimum of 135psi with a maximum variation of 28 psi. I am assuming that this means that it can be higher. And that the maximum variation is the bigest variation between cylenders and not the highest the compression can be (135+28 163psi). and that my readings are good and I bent no vavles is this correct???</TD></TR></TABLE>

Minimum = 135 psi (you passed)
Maximum variation = 28 psi (you passed) 180-165= 15 psi, i personally think that maximum should be around 10-15

So it is within "specs". Depends on engine (compression ratio) what the "avg" should be like your engine is putting out 165-180 but other engines such as the b-series put 200+ .

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bgoetz &raquo;</TD></TR><TR><TD CLASS="quote">I have never done a compression test before # 2 was kind of weird and made a loud chirp. It kind of freaked me out so I don't think I cranked it as much as the rest. I will do it again this time I will be sure to crank it the same is there any specific # of cranks???</TD></TR></TABLE>

You should turn the car over atleast 3 times, after that the compression should stay where it is.