GM rod and Main Numbers

[Anthony P.]

Today I was able to remove the pistons and Crank, from my 66 427/390.. Looking to see if the #s on the brg shells are original?

Rod Brgs. GMM 420
57831
30185

Main Brgs 52894
001
267M5

Joe L What if any useful info is this? What do the old parts books say?

[Joe L.]

Re: GM rod and Main Numbers

Today I was able to remove the pistons and Crank, from my 66 427/390.. Looking to see if the #s on the brg shells are original?

Rod Brgs. GMM 420
57831
30185

Main Brgs 52894
001
267M5

Joe L What if any useful info is this? What do the old parts books say?

Tony-----


None of these numbers are GM part numbers or, apparently, derivatives thereof. However, I believe the rod bearings are original-----the "GMM" denotes General Motors-Moraine. The main bearings may or may not be original. Here are the original GM part numbers:

main bearing positions 1&2-----GM #3885380

main bearing positions 3&4-----GM #3876080

main bearing rear----------------GM #3876085

rod bearings----------------------GM #3876091

One note of caution, though: all of the above are standard size bearings which is what the factory generally uses. However, sometimes a non-standard size bearing is used for one or more positions.

[Anthony P.]

Re: GM rod and Main Numbers

Joe, I forgot to state that the mains also have the GMM 420 as well. I will bring home a micrometer from work tomorrow and get a measurement of all journals before I order new brgs.

Anybody pros/cons on the Clevite P series brgs?

Thanks Joe

[Joe L.]

Re: GM rod and Main Numbers

Joe, I forgot to state that the mains also have the GMM 420 as well. I will bring home a micrometer from work tomorrow and get a measurement of all journals before I order new brgs.

Anybody pros/cons on the Clevite P series brgs?

Thanks Joe

Tony-------


My preference: Federal-Mogul Premium Aluminum (AP-series). These are equivalent to original GM.

[Anthony P.]

Re: GM rod and Main Numbers

Ok thanks Joe, I just looked on their e catalog and found the A series, have not found the the AP series yet.