My mechanic lost my main bearing caps

[51BuickWoody]

I'm having my 51 Straight 8 (263) rebuilt. I bought new rings, pistons, bearings and a few other parts. The shop that is building the engine called me to tell me that they lost 1 of the main bearing end caps. Anybody have any leads on where to find them?

[nickelroadster]

Sounds to me that they should be the ones to find one for you.

[JFranklin]

The shop that lost it should have the wherewithal to make a new one, or know a shop that can, if one cannot be found.

[g-g-g0]

I would suggest that you drop down to the Buick section of the forums and post your needs on the Post War forum. Lots of Buick eyeballs there.

[Jolly_John]

Hard to believe a professional engine shop would lose something like a main bearing cap. I'm thinking "good luck with their rebuild". Now, on a more positive note, this should be an easy straight eight BUICK part to find. I suggest you post on the BUICK Buy/Sell section here on the website. Here's a link to that area. Someone there will have the bearing cap you need. John

 

https://forums.aaca.org/forum/12-buick-buysell/

 

P.S. It looks like g-g-g0 and I were posting at almost the same time! I hadn't seen his post.

Edited March 4, 2023 by Jolly_John (see edit history)

[viv w]

Your main bearing caps are line bored on the block at the factory and it is unlikely that a replacement cap will be identical even if you find one. Even with a replacement cap they will probably have to rebore the journal, this may or may not be possible.

Without the original bearing cap the chances are that your motor is scrap, time to find another motor or tell the machine shop to buy you another one.

[JFranklin]

A bit fatalistic I think. Anything can be done at a price. Hey we went to the moon after all.

[Bloo]

Maybe, but it is also true you can't just throw another main bearing cap on. An automotive machine shop should be able to fix that, but 99% chance it will need align boring. Back in the day any block with a missing cap was considered scrap, but back then it was easier and cheaper to just get another block. Nobody wanted to add the cost of align boring to an engine overhaul. Today it may be worth doing.

 

That said, any automotive machine shop knows all this, and the fact that these guys lost one is a really big deal. I wonder if they even know which one goes on which saddle and in which direction? I think I would cut my losses, get my stuff, and find someone else to clean up this mess. Yes that is probably more expensive, but I just couldn't trust them to do anything right after this.

 

Sorry about the rant. This makes my blood boil. Anybody got a scrap 263 block laying around with some caps still hanging on it?

 

 

 

[Luv2Wrench]

Hard to believe they lost the cap but maybe easier to believe it was knocked off a table or dropped and damaged/cracked.  I'm with @Blooon this one.  This is your sign that you've got the wrong machine shop.  At the very least the communication that came from them should've been "we've had an issue with a main bearing cap, we're sourcing another one now and will line bore when it arrives, all at our cost."

[JV Puleo]

My first reaction to this problem was exactly what Bloo has said but I am not familiar enough with "modern" engines to feel qualified to comment. Several years ago my cousins overhauled a bit diesel engine. Cousin George, who put the caps back on, didn't know they had to go on in exactly the same place and direction. As a result, the engine seized up almost immediately and they had to do that part of the job over. I'm presuming this has insert bearings and if it is line bored are there insert bearings that are oversize on the OD available? This sounds like a much bigger problem than just replacing a cap.

[NewOldWood]

38 minutes ago, JV Puleo said:

. I'm presuming this has insert bearings and if it is line bored are there insert bearings that are oversize on the OD available? This sounds like a much bigger problem than just replacing a cap.

What they should do is remove enough material from the mating surface of the cap to make the bore slightly undersize, then bore it back to original spec.

[JV Puleo]

I hadn't thought of that but it's still tricky because it will only be undersize top-to-bottom.

[Bloo]

3 hours ago, NewOldWood said:

What they should do is remove enough material from the mating surface of the cap to make the bore slightly undersize, then bore it back to original spec.

That's how it's done, but you would have to lose a little metal at the top of the bore. Obviously they try to take mostly from the bottom to minimize that. It does alter the distance from the camshaft slightly, and if there is a timing chain, it will probably run loose. For super common engines like a smallblock Chevy, you can get a slightly undersize timing chain set meant for engines this has been done to. With timing gears, I don't know and I don't recall ever hearing it discussed. You might need to lap them.

 

 

Edited March 5, 2023 by Bloo (see edit history)

[JFranklin]

Could the donor cap actually fit close enough to work without machine work? Could a cap with too much bore be spray welded and machined to match the original? What if the cap is undersize? I doubt the engine is trash, I'm an optimist.

Edited March 5, 2023 by JFranklin (see edit history)

[AURktman]

3 hours ago, JFranklin said:

Could the donor cap actually fit close enough to work without machine work? Could a cap with too much bore be spray welded and machined to match the original? What if the cap is undersize? I doubt the engine is trash, I'm an optimist.

I picked up a small journal 327 Chevy that was missing its main caps, found a set on eBay, had my machine shop line bore it and it all worked perfectly.  Those small journal blocks are tough to do a main cap swap on though.  They need to search their shop and find your cap.  Either they lost it by tossing it in the trash accidentally, lost it by ruining it somehow, or they lost in on someone else’s engine they are building.  If none of those three are accurate then it’s probably under one of the machines and they’re just too lazy to bend over and look.  

[playswithbrass]

Don’t panic,as long as you get another cap all is well. Any good engine rebuild will start off with line boring the main caps and then decking the block so you have the two surfaces parallel then engine is bored. Doing this gives you a fantastic base on which will be a well built engine. We used to do this with old blocks(seasoned) that were being built for racing,look at this to be a positive. Knew a guy who would buy complete engines from Ford for racing first thing he did was install it in his tow truck and drive the#$&* out of ( block now seasoned) and would not shift after the line bore etc.   Shop should do line bore for free as they lost the cap. Again no big deal cheers pete

[edinmass]

 

More tractor mechanics…….just toss in another cap from a different engine. I’m certain that if they ask for another cap, they are not capable of doing anything right. Run……,run fast and long.