RedB.
Well-Known Member
I was wondering how much cylinder wear is too much before a new bore is necessary. We have a 5.9 magnum block that shows 5 thousands over and was wondering if we could get away with a fresh hone and new rings ?
If the bore was round and straight, and not tapered, you could; but that's only the half of it;
you still gotta deal with the ridge at the top of the bore, and
what do you do with the huge ring-gaps with grow by 3.1416 times the wear; which in this case is close to .016?
and finally,if the bore varies from top to bottom,(tapered) then the rings are gonna walk into and out of the grooves, accelerating the wear on those parts.
All in all, IMO, a bad deal.
Theoretically you could solve some of those problems, but it would probably be only a short term solution
Yep that is the right move if you are not just tossing it together. We had a block where the bores were exactly .005" over, no taper or out-of-roundness; it was a block machined for a drag race application. Even .005" perfectly straight bores were not acceptable to me for hyper pistons in street use, so we went to .020" overbores.
Thick, straight, round make power.
In that case, selecting the right compression pistons, for your cam is gonna be important
Yes the Magnum block is nominally .015" shorter.... 9.585" vs 9.599" or 9.600". Performance pistons will be the same pieces, ending up at a different deck height. One rod type is a bit wider at the small end, where the pins go through the small end and piston. So some rods have to get ground a bit thinner at the small end to fit between the pin bosses of certain pistons. Not a big deal.For sure, when the time comes I will consult you and the other Motor Heads on FABO . I don't know what is available for the Magnum 360 vs la 360, iirc the magnum has a bit shorter deck ?
Yes the Magnum block is nominally .015" shorter.... 9.585" vs 9.599" or 9.600". Performance pistons will be the same pieces, ending up at a different deck height. One rod type is a bit wider at the small end, where the pins go through the small end and piston. So some rods have to get ground a bit thinner at the small end to fit between the pin bosses of certain pistons. Not a big deal.
Heads are different but interchangeable with some limitations, and the Magnum are all roller cams. IIRC, damper weights and flexplate/flywheel weights are different too. Probably more stuff that I can't think of right now.....