Originally Posted by loxx101
The bores cleaned up fairly well but not perfect. Gapped anyway and they read 15.5 thou. The book states between 10 and 14 thou so unfortunately (or fortunately, whichever way you look at it) it's going to need a rebore.
Since I now have to get that done (and of course, new pistons) then it'll be 0.040 oversized but perfect bores and perfect gap. Gonna cost a bit but there you go, at least it'll be right.
This is complete rubbish,and I'm surprised no-one picked up on it.I don't read every build thread,and expect technical issues/queries will end up in the technical section,or more often the general forum.
For any practical purposes,it wouldn't matter if the ring gap was 0.060" as long as the rings otherwise fitted well.You would be hard-pressed to notice any difference in performance or oil consumption.
The most worn T140 cylinder I've re-ringed had 0.007" taper/wear.That's enough to increase the ring gap at the top of the cylinder by 0.022",compared to the lower part of the cylinder.So if I had 0.012" gap at the unworn part of the cylinder,it would be 0.034" gap at the top of the cylinder.
Did it run fine with a hone and re-ring?Yes,of course.It still ran fine 20 years later (never been apart since).
I would always recommend you use about 30% bigger gap on the second compression ring,compared to the gap on the top ring.It helps the top ring to seal,increases power,and reduces oil consumption.
If you had 0.010" on the top ring,0.013" on the second ring.