Doing compression check; what are the numbers I need?

[LXSTASY]

This Saturday I plan on doing a compression check before I go gung-ho on my HCI install. What are the numbers and average numbers I should be praying Friday night to get?
I've read 125-130, but then another post was suggesting 200 (which I think is wayyy to much), but non the less I still am confused.
Any numbers or tips would be great
Dan

 

[Ourobos]

Depends on different things.. You really want to see all eight numbers withing 10% of each other to be good to go.

 

[90mustangGT]

As long as they are above 70psi and within 25%, so your good. The compression test numbers have a lot to do with the cam and other factors.

edit- 10% is what you really want as mentioned before, but 25% is "acceptable" but not nessasarlly good.

 

[double drop top]

A leak down test is more important then the compression test. But I always do both to get a complete picture of the condition of my engines.

 

[HISSIN50]

And though testing means differ, I would really not want to do a HCI on a motor which did not have even compression and a mean number of ~125 PSI (if you get lower numbers, at least do a Leakdown test first!).

Good luck.

 

[LXSTASY]

Yea thanks guys,
I will do it and see what I come up with