454 rebuild: complications already

[zac]

This engine has been sitting for 22 years since I pulled it out of my '74 Monte Carlo. I didn't have any history on it, and if I did I would have forgotten it by now. I pulled the heads off, breaking one bolt. Just by looking at the valves, they looked a lot better than I would have thought. Nothing obviously burned. This car had a little over 100K on it and ran fine when I pulled the engine. I was also surprised to find basically no ridge at the top of the cylinder. The one piston I have pulled basically popped right out. The pistons have no indication that they are oversized, and I have looked VERY closely. They all just have an "8" stamped on them about a quarter inch high. Seemed stock.

When I flipped the engine over to stamp numbers on the rods, I saw that it had already been done, a pretty obvious indication that someone had been in to it. None of the rod bearing showed any indication of being oversized, but they did look to my like 100K+ bearings. Mains 3-5 had no oversize indications, but 1 and 2 had "0006" stamped on them. I think I know what's going on here, but I don't want to say until I get some feedback from you guys. The timing chain was very loose with the stock aluminum/nylon gear that was in surprising good condition. The crank gear was cracked with a tooth missing and indications it was poorly installed. The lifters popped right out with no sign of mushrooming.

My wild guess is that this engine had rings, a cam and valve job done at some point, but the bearings weren't touched for some reason.

I do not have a micrometer/snap gauge for this size bore. I'm thinking it is stock. I am mainly interested right now in what people think of the "0006" on the mains. Unfortunately, because of a massive hours cut at work, this project has to be low buck. If it gets to where I can't do a stock rebuild without lots of parts and machine work, I'll have to shelve it.

[JMac11]

Get the crank mic'd by a machinist, it will be worth the head ache. I suspect it is a tad undersized from GM. Have seen .010 over pistons oddly enough in 2 different 455 Olds from the Factory. my 2 cent

[Jonboy]

I would definitely have the crank mic'ed. If the pistons are oversized, it will be stamped on the top of them. Clean them up with a wire wheel to make sure before you order rings (also make sure to clean the ring lands really well, too, if you are going to reuse the pistons..... that's experience talking). If you have access to a mic set, check to make sure the bore is good the length of the cylinders, and clean it up really well. Also check the cam bearings, it may be worth replacing them if they look worn. A machine shop will usually do this pretty cheap. It beats renting a tool and wasting a cam bearing set first.