Low compression, weighing options.

Patton wrote:

Thinking "honing" is simply de-glazing cylinder walls so new rings can seat. And that boring (not honing) is needed to bring an oval cylinder to specs. Could result in a "de-glazed" oval bore.

Perhaps the machine shop was engaged to do a valve job and to de-glaze the cylinder walls with a honing brush, but not requested to measure the bores or test fitment of pistons or rings.

Is re-sleeving not a feasible option?

I believe yer right here General... He did say "honed" and not "bored". He may now have perfectly cleaned, oval bores... would explain why he said the rings were within spec when inserted, why he felt no upper cyl. groove or elevation change yet still have poor compression readings.

wrenchmonkey wrote:

Patton wrote:

Thinking "honing" is simply de-glazing cylinder walls so new rings can seat. And that boring (not honing) is needed to bring an oval cylinder to specs. Could result in a "de-glazed" oval bore.

Perhaps the machine shop was engaged to do a valve job and to de-glaze the cylinder walls with a honing brush, but not requested to measure the bores or test fitment of pistons or rings.

Is re-sleeving not a feasible option?

I believe yer right here General... He did say "honed" and not "bored". He may now have perfectly cleaned, oval bores... would explain why he said the rings were within spec when inserted, why he felt no upper cyl. groove or elevation change yet still have poor compression readings.

Yep. This is the theory I am operating on right now. You are correct that the cyls were NOT bored, just honed (de-glazed). And I never asked the machine shop to check for round. Woulda shoulda coulda. So that's why I'm thinking that they may be ovaled.

depending upon the shop and who did the work, if they just used the "ball" type hone then it will only lightly deglaze the cyl, which could be a reason that the rings did not seat.
If they used a spring type hone, looks like a big brake hone, then the cyls are prob out of round still.
And last if they used a sunnen hone the cyls will be round and at this point way over spec in bore size, but you said you checked ring gap, how did you make sure the rings were square to the bore when you checked them?
are you sure that you did not break the top rings during assembly, it would be odd to get all four of them but just asking

Last I have seen bad rings before, its not very common, but I have seen it and no matter what you do they are not going to seal and you will be burning oil