Compression Numbers

[dobie]

Here's a picture of the compression numbers for my 383. We did this on Saturday. Cylinder #4 was re-tested wet and nothing changed, indicating no valve problems.

Anyways, what say the experts here?


:cheers:

 

[Basketcase]

well I 'm no expert,but from what I remember, they all seem to be close as far as the readings. so that's better then one or more way different form the others.
now I'll step aside and let those who know have the floor.....

 

[ACME A12]

Dobie - I'm no expert but here's my :cents: :

1) I agree with your conclusion after the wet test on #4 - I was always taught that if the number went up significantly that this was indicitive of a problem with the rings. Little or no change meant everything was likely in good working order.

2) The difference between the cylinders is what to really watch for (yours vary from a low of 140# to a high of 160#) and you only have a max deviation of 14%.

3) Based on my #2 comment above I would not be the least bit concerned about cylinder #4 being a little lower than the others - the overall numbers and their range are of greater importance.

Ray

 

[Big John]

The numbers look good to me also.

 

[69hemibeep]

Run it

 

[dobie]

Sounds great! That was our conclusion too, but second opinions are always a good thing!

Thanks!!

 

[hotrod98]

I thought that re-testing wet with no change indicted no ring problems. On a cylinder re-tested wet with no change would indicate a valve problem. I'm old and my memory isn't what it used to be though.
Your numbers look okay to me.

 

[dobie]

Well, I was told that wet testing with change indicated a valve problem. No change could either mean a ring problem, or that that cylinder is fine, with just low(er) numbers.

Who knows. :huh:

Thanks!

 

[Big John]

If the pressure goes up when tested wet, it indicates a ring problem. The oil seals the rings.

 

[moparstuart]

it's a good motor from your number go ahead and use it
maybe use some of that restore stuff , it fills the cyclinder wall cracks , scratches and may even out your compression ratio's

 

[dobie]

Thanks for the clarification and information. In the next few months I'm gonna put on a set of re-worked 906 heads, headers, and an XE-274H cam.

Hopefully this set up will last a few years, until I can afford to either do a full rebuild on this 383, or a rebuild on my 440 block.


:drive: