Slant Six Forum :: Questions about Main bearing caps

I recently got a couple of engines, one was previously disassembled.

The disassembled engine does not appear to have the main bearing caps numbered.

I have been under the impression that they need to go back in the same place they were removed from...

If that is true, or best practice, any suggestions on how to accomplish such?

I have never seen main caps that were not numbered. I suppose it is possible. Most forged crank block engines have caps cast with a number on top of a raised circle.

Quote:

I have never seen main caps that were not numbered. I suppose it is possible. Most forged crank block engines have caps cast with a number on top of a raised circle.

Thanks Greg,
I will look again!

Author:	Jase [ Tue Apr 28, 2026 5:57 am ]
Post subject:	Questions about Main bearing caps
I recently got a couple of engines, one was previously disassembled. The disassembled engine does not appear to have the the main bearing caps numbered. I have been under the impression that they need to go back in the same place they were removed from... If that is true, or best practice, any suggestions on how to accomplish such?

Author:	Greg Ondayko [ Tue Apr 28, 2026 6:32 am ]
Post subject:	Re: Questions about Main bearing caps
Quote: I recently got a couple of engines, one was previously disassembled. The disassembled engine does not appear to have the main bearing caps numbered. I have been under the impression that they need to go back in the same place they were removed from... If that is true, or best practice, any suggestions on how to accomplish such? Yes, that is correct. When the blocks are machined, the caps are line-bored into position. They need to remain in that position when reassembled. If they have been swapped, it will likely need line bored again or additional machining work to get the caps to work in the new position. I have never seen main caps that were not numbered. I suppose it is possible. Most forged crank block engines have caps cast with a number on top of a raised circle.

Author:	Jase [ Tue Apr 28, 2026 6:51 am ]
Post subject:	Re: Questions about Main bearing caps
Quote: I have never seen main caps that were not numbered. I suppose it is possible. Most forged crank block engines have caps cast with a number on top of a raised circle. Thanks Greg, I will look again!

Author:	Greg Ondayko [ Tue Apr 28, 2026 7:13 am ]
Post subject:	Re: Questions about Main bearing caps
Quote: Quote: I have never seen main caps that were not numbered. I suppose it is possible. Most forged crank block engines have caps cast with a number on top of a raised circle. Thanks Greg, I will look again! Get yo'self a stiff wire brush and some brakekleen, gasoline, or some other crud/ goo removal chemical/method, and you may find them! Good luck! Greg

Author:	Rick Covalt [ Wed Apr 29, 2026 1:17 pm ]
Post subject:	Re: Questions about Main bearing caps
Yes, I never saw mains not marked either.

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