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cyl compr test.



I did a cylinder compression test on my 68 big block.
This to ensure that the broken exhaust valve rocker did not leave any damage, like U/S valve seat, piston rings.
Looks like if all cylinders pull right over 11 Bar ( 160 PSI ).
I hope the difference between the piston pressure comes due to the old , original untouched L71 heads solid lifters.
What do you think ?
Thanks Gunther



If all the cyls have +/- the same compression then you're ok.
My 454 has been sitting for over five years. I filled the cylinders with WD-40 and let it sit for a week, then turned it over. Static compression is 175# on all but #2, which is 160#. I'm pulling the heads anyway to do a good three angle and deshroud job, so I'll probably have them even when I bolt it back up.
If I remember right, you can raise the compression test value by filling the pistons with oil.
This is one way to eliminate bad piston rings from leaking valves.
Recheck the low ( 160 ) first without oil, than fill some oil and do the test again. If you see a big difference, should be the rings.
Than again, I got told that a 20 % difference between piston pressure is standard, 10 % is still very good, so don't worry.
You're right Gunther. That's one reaon why I'm doing a valve job!

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