oldsonharmont

I had my spare 455 block thermally cleaned and checked. The engine shop said the block would need to be bored out due to rust in one of the cylinders. Yes, the motor sat outside with no intake or exhaust manifolds before I got it.

If I go forward, what should I expect to happen, and what might it cost?
Is .030 a standard overbore, and then new pistons and rings right? It sounds like they can reuse my original rods.

Thanks

jag1886

You need to be asking your shop this, they should be able to tell you if a .030 overbore will clean it up and what it will cost (yes .030 is standard), your rods can be normally be reused just get them resized.

Octania

that's only a 0.015" cut
much rust at all will require more.
Let the machine shop decide.

dfoisy

See if they can id the worst cylinder and have them start on that one. Just had this problem on a 402 build. Had to go .060 over to clean one bore. Any more and it wouldn't have been worth the money for them to bore them all and end up with a scrap block. If that makes any sense?

oldsonharmont

That makes a lot of sense, thanks. The pitting in one bore looks slight, but I'm not the expert here. The shop said they could go .030, .040, or .060 over to clean it up, just depends. I've also heard stories about blocks being bored .060 over then running hot.

My neighbor is doing this as a side job at his shop, so I'm getting a break on the machine work. I don't want to push his generosity too far, or pour money down a hole either.

507OLDS

The later 73-77 blocks usually don't have as much material to bore past .060,compared to the earlier blocks.Can you determine what year the block is? I had a similar issue with a 71 455 block.It was a complete engine that sat in a car,with a hood,but in a junkyard for many years,so one cylinder did have some questionable rust.That cylinder was bored first.It went to 4.200",and still had a tiny dingleberry in it,but was down low,and didn't pose a problem.This was for a race application,so custom pistons were being made anyway.It has been fine ever since.
The shop should be able to determine how much needs to come out,to remove the pits.

oldsonharmont

The block we're working on is the numbers matching 'F' casting that's original to my '71 SX. I'd like to have this engine rebuilt and reinstalled, but I just want to know when it's time to quit. Right now I'm looking at at bore job and new pistons. Could the bad bore be sleeved instead? Comments are welcome, thanks.

Professur

If nothing else, they can always sleeve it.

oldcutlass

Was there not a plan for the end result? .030, .040, .060 are standard bores for off the shelf pistons.

507OLDS

If it is the original block to your 71 SX,then continue to pursue. Have them start with the bad cylinder,go .030 or .040,and see how it turns out.If not,go .060. If it is that bad,and .060 will not clean it up,then have it sleeved. Again,the shop should be able to determine what it will take to clean it up before doing any unneccasry boring.
It could be worse.It could be cracked.

Professur

I've often wondered why they don't just drill and fill cavities like that like a dentist.

oldsonharmont

The idea was to clean up the original block for a stock rebuild. Since the engine sat open for years, I wasn't sure what to expect. As I mentioned earlier, I'm getting a break on the shop work, and don't want to push my neighbor's generosity or a bad block too far. The good news is we didn't find any cracks. I hope that makes sense.

oldsonharmont

I stopped by the engine shop today and got an update that my block was bored .040 over and they have a set of used Keith Black forged pistons to fit the new bore. They will reuse my old rods and the rebuild is stock otherwise. Does this raise any concerns, and what is the new displacement now? (455 @ .040 over)

507OLDS

That will give you a 464".
One of my concerns would be the condition of the used pistons. Is it a coincidence that your block needed to go .040,and the shop already has those pistons?

nsnarsk65cutlass

I don't get it you stated my spare, then numbers matching later on?The machine shop will determine how much is needed to clean up the cylinder or if a sleeve is required. Nick

oldsonharmont

That's a good catch Nick. While this block is original to the car, it's not in the car at this time. There's a 455 from a '70 Delta 88 currently in the car, and I got the original engine when I bought the car in '08. It's been sitting for a while, and I finally wanted to see what I had there.

As for the .040 overbore, I've known my engine builder since 1969, and he's also my neighbor. He's a former drag racer, and retired speed shop owner. He's doing my engine as a personal project in his son's rebuild shop. The pistons are from a 455 Olds boat motor that he already had. I asked for a quote the other day, and his charges are about half the going rate. You don't catch a break like this everyday, so I'll just smile and say 'thanks'.