dustysfe

this may sound dumb but i dont know much so here it goes, i have a 62 ford truck that had a 352 big block i had it rebuilt 3 years ago said they bored it to a 428 its has a set of cobra jet heads that i picked up a swap meet number match to cobra jet heads. i recently crapped a wrist pin on cylinder 3 engine was knocking ive pulled it out and dissassembled. im getting a bore size of 4.132 which is 428 right but the pistons say .090 stamped on the top are the pistons to small for this engine with to much piston to wall clearance they are speed pro pistons. any help to this question would be helpfull. also every one of the cylinders is showing scuff marks on the cylinder this is why i thought they may not have been the right size causing the knocking not long after the rebuild the builder died so i cant ask him now, thanks dusty

kdtrucker

Sounds like you answered your own question... A 352 has a bore of 4.00. If you have a bore of 4.132 and a piston of .090, you need to make up .042 of empty space around the piston and the rings are going to work hard to fill a gap that big. I'm surprised you only lost one piston. Why didn't the engine builder use stock 428 pistons, another factor,...how much of the cylinder wall is left after cutting .132 thousands out of it, even if it was the HI-PO 352 there isn't going to be much left.

If that block is all you have take it to a local machine shop and let them check it out to make sure it's still OK and if so, hone the block just enough to clean it up and use 428 (4.130) pistons. Make sure you watch your temps. after you get it running.

If you can get another block, maybe a 390, (4.050 bore) and if the pistons (.090) are salvagable,... bore that block .040 thousands and you'll be in better shape.

dustysfe

major mistake on my part after i finished pulling it apart today the bore is a 4.105 not even close to a 428 like it was suppose to be and the pistons are 060 over speed pro's, and all the bearings are showing brass all ate up, the builder was evedently an idiot and a liar for telling us he was building a 428 when it was just a 390 with the cobra jet 428 heads that i purchased

kdtrucker

Well sir ...with information all the cylinder wall must be scared to sh*t!! Because now you have a block at 4.105 and .060 over (from 4.050 I assume) that leaves you with .055 thousanths. I don't know how he even got them in, - in the first place!! Well like I said, clean up the scaring and get the right pistons. As for the bearings being all chewed up....the man didn't beleive in washing the engine before building it.

Check tour heads, there should be casting numbers between the two center spark plugs. It should read C8OE 6090 N if it dosen't there not CJ

kdtrucker

I got to thinking and he more than likely cleaned your engine,...but with the stress of having pistons too small for the cylinder more than likely is what took a toll on the bearings.