[justincampbell]

This might be a dumb question, but since I only throw things out when they beyond saving, I have to ask anyway.

I have a set or two of OHC 6 main caps that are pitted on the surface that the bearing lays in. Some of the pits are as big in diameter as a pin. Since this is on the back side of the "important" surface, can they still be used? Or are they junk?

Sorry I didn't take any pics yet. I can get some if this is not just a black and white, yes or no situation.

[Dragncar]

Are you talking "pin" like the size of a needle ?
For just as basic engine I would not worry about something that small.
Now it its the size of a main cap dowel pin that is different.

[steve25]

If there got to be rust to get delt with Some pitting is better and can be tolerated more then a complete layer of total surface rust.

Removing a layer of rust as in this photo will make the main bearing bore bigger in which case a line hone job will need to be done on the block.

[694.1]

Those bottom ends are pretty sturdy. Just take it easy on the nitrous!

[hurryinhoosier62]

Originally Posted by justincampbell

This might be a dumb question, but since I only throw things out when they beyond saving, I have to ask anyway.

I have a set or two of OHC 6 main caps that are pitted on the surface that the bearing lays in. Some of the pits are as big in diameter as a pin. Since this is on the back side of the "important" surface, can they still be used? Or are they junk?

Sorry I didn't take any pics yet. I can get some if this is not just a black and white, yes or no situation.

Depends on the size and depth of the pits. Pitting could lead to cracking, but I have never seen a main cap crack simply from pitting alone.

[mgarblik]

The most important factor from your initial post is to make sure all the caps are still assigned to a particular position and to a particular block. No mixing and matching! The rust, unless really bad can be dealt with from a line hone which is probably needed anyway with that long block. When this is done, make sure the machine shop understands this is an OHC engine. They may not realize this 50 years later. As material is removed to line hone, the camshaft timing will retard slightly. Not much of an issue unless they really go crazy or this is the 2nd or third time it's been line honed. You really don't have much choice re-using these caps. As hard to find as the OHC blocks are now, you don't want to scrap them unless really not usable.

[justincampbell]

Thanks for all the input.
I cleaned them some more and I think they actually look worse now than before. Here is a picture of one of them.

[mgarblik]

Originally Posted by justincampbell

Thanks for all the input.
I cleaned them some more and I think they actually look worse now than before. Here is a picture of one of them.

How is the block surface where the cap has to register? If it looks like the cap register and is pitted that badly, it's probably game over without spending considerable $$ to have the block surfaced. If the block surface looks normal and smooth, I will make you this offer. Pick out your worst cap and send it to me. I will grind the cap and record how much material was removed. Then you can make a decision about line honing it. Cost will be shipping only. PM me if interested.

[justincampbell]

Originally Posted by mgarblik

How is the block surface where the cap has to register? If it looks like the cap register and is pitted that badly, it's probably game over without spending considerable $$ to have the block surfaced. If the block surface looks normal and smooth, I will make you this offer. Pick out your worst cap and send it to me. I will grind the cap and record how much material was removed. Then you can make a decision about line honing it. Cost will be shipping only. PM me if interested.

I appreciate the offer. Sadly, I suspect the block surface is in similar condition. There were 2 OHC engines(1 sprint, 1 base) that were disassembled probably 40 years ago and then set aside and forgotten. I am just trying to salvage what I can on behalf of the owner's family.
Here is a picture of the 2 blocks.

[mgarblik]

After seeing the pics of the blocks, I suspect your right. Can they be saved?. Yes. The blocks could be thermal cleaned, pan rail, main registers machined, then line honed. Is all that work worth the cost? I doubt it. Even at this stage of the hobby, there are probably some better cores out there. JMO.

[justincampbell]

That's what I was afraid of.