Main bearing caps

[MMorse]

Good evening! I rebuilt my '13 engine this past spring and had cause to pull it again to fix a couple of things (one of my own mess-ups and one from another guy). The main bearing caps caught my eye as two seem narrower than they should be. Plus, there are a couple of gaps that concern me. Someone else who rebuilds Model T engines did the machining and re-babbiting. See attached pics. Any cause for concern?

[Kerry]

They are caps that were supplied by Dodge Brothers, normally they would be poured with Babbitt to run flush with the block saddle, and a radius cut each end for the radius of the crankshaft. The number 3 is OK as for number 1 and 2, not right but if you are not looking for an engine to last for ever, will still do the job.

[Kevin Pharis]

Only the rear main bearing cap is equipped with thrust material. Your bearings look typical to me. I suspect your center main bearing gap (noted in pic) is simply an over zealous radius on the bearing material. I have had cranks reground where they did not grind all the way into the radius, solution was to relieve the end of the bearing similar as you have shown. If it was running quiet, it’s probably fine. Or you can pull the cap and plastigage to check clearances

[MMorse]

Thank you, Kerry and Kevin. I'll plan to put it back together and run it. No knocks this summer, so all should be good. I don't know why I hadn't noticed this in the spring when I got the block back, but I wasn't sure whether to be concerned or not when I noticed it this past weekend. Thanks again for your help.

Mike

[Adam]

Who did the babbitt work?

They should have known the difference in early caps. With that being said, if clearances are good, and the crankshaft grinding job was good, your longevity on those #1 & #2 main bearing caps likely will be less than it should be and they are more likely to “burn out” under heavy loading or poor oiling conditions, but they will still “work okay” if you don’t lug the engine and/or drive too fast. My advice is to just keep using it however you want until you have bearing problems, then take it somewhere different to have the bearings re-done. A high quality babbitt job will also have the 3rd main saddle re-machined to accept babbitt thrust surfaces and machined faces just like the cap. This extends the life of the 3rd main thrust significantly.

[Mark Gregush]

While the rear cap is self-evident, the center cap is just a bit wider than the front. The front pretty much covers the saddle; the center one does not fully cover the saddle. As said, the rear cap carries the full thrust by itself no thrust is poured in the block, some do add it there too but the block has to be cut back to add.