Piston stamp 58 bore?

It's possible, but that isn't standard practice. Maybe the engine shop that rebuilt the engine measured the pistons and they were .058 oversize, which would be about right for a .060 overbore assuming .002 piston clearance. The best way to know for sure is to have someone with the proper measuring tools measure the bore diameter. For reference purposes you could even use a dial caliper to check it and be within .001 or so, which would be acceptable. The stock bore is 3.750 and .060 overbore would measure 3.810.

Chris

Thanks for the reply Chris,

I thought it unusual for two blocks to have the same stamp on the pistons. Could this be a stock numerical representation? One of the blocks is an 84 and one is an 85. He said the current one in the jeep (85) has been driven not much in the last 10 years since he had it. If true that would make it going from stock to 60 over bore within 10 years. Possible but seems a little extreme doesn't it?

Thanks,

Bill

I have a feeling that is some type of factory stamping, but someone like Mike or Bill H. would know more about that than I would. I wouldn't think that someone would intentionally bore an engine .060 over on it's first rebuild, unless it was necessary. Most times .020 or .030 will do just fine for the first overbore. Stranger things have happened though.

Chris