.060 Overbore

[dkg4244]

Alright folks,

First post here. I have a bit of a handle on this stroker business but I have a few questions that maybe some of you with experience can help me out with. First, my backstory on my engine. I have an 83 Scrambler that has (had) a 4.0 swapped in. It's running OBD1 and is a '93 vintage setup. At some point, this engine was gone through and "rebuilt". I pulled it because of a rod knock that would come and go. Oil pressure was great at about 60 psi at all times including idle. I tore the engine down and found that the #2 rod bearing was toast. After I checked all the other bearings I found that most had started to wear through the first layer on the bearings and some of the mains had pretty bad scoring, evidence of oil contamination or starvation. I measured the crank and it is .010 under on the mains and .020 on the rods. Here's the kicker, the #2 rod had a standard bearing while all the others has .020 under!!!!! What the heck!?

The crank is junk. So I checked the block and it's .060 over with new pistons. The bores are still good with no taper and hone marks still clear on the walls. There is some scoring from the piston skirts though which is a bit odd and kind of looks like an overheating issue. The ring gap was at .038 when the stock gap is .009 to .024. It looks like this engine was slapped together. Supposedly it has about 15-20k on it and i believe it from the cleanliness of the pistons and the cylinder walls. I haven't measured the deck height of the block yet.

My question is this, is 0.060 over too much bore to have a reliable stroker? Do I have enough metal in the block left for adequate heat transfer?

My head looks great and the cam and lifters look new as well. Is it worth it to consider using this block for a stroker build or should I look for something else?

Thanks,

Dave

[sly-jeeper]

gross that's no fun man...to be safe you would have to sonic check the walls...maybe the thin walls are overheating and scoring...by the sound of this you don't have much left of it..im worried by the time you hone the scratches out you cylinder wall clearance will be to high if it isn't already

[Cheromaniac]

My question is this, is 0.060 over too much bore to have a reliable stroker? Do I have enough metal in the block left for adequate heat transfer? Is it worth it to consider using this block for a stroker build or should I look for something else?

A 60 thou overbore isn't an issue. The only thing that could prevent you from reusing the same block for a stroker build is if the cylinder walls are scuffed badly enough to need another rebore. You could go to an 80 thou overbore but that would require sonic testing the cylinder wall thickness and the use of custom pistons. If the block fails that test look for a replacement.