The Ford Barn

The Ford Barn (
-   Model A (1928-31) (
-   -   Engine Bearing Shims (

juke joint johnny 03-04-2020 04:30 AM

Engine Bearing Shims

What was the thickness of the Rod and Main bearing shims on the A& B engines when they were new?

I think we should use that as a guide when pouring new bearings

Bob C 03-04-2020 11:47 AM

Re: Engine Bearing Shims

I think Vince has the information you are looking for.


juke joint johnny 03-04-2020 02:54 PM

Re: Engine Bearing Shims

Thanks Bob that's a big help !! Not much old Vince doesn't know

Kurt in NJ 03-04-2020 03:54 PM

Re: Engine Bearing Shims

The original engines that I have taken apart have 2 shims on each side that are about.002 each thick---- if the cap has been cut it may need more--- I have checked the rear cap bore to slinger--- too many shims and it will have too much clearance-- leaks--- conversely if the cap has been cut in the past more shims may be needed to prevent rubbing of the slinger

Kohnke Rebabbitting 03-04-2020 04:06 PM

Re: Engine Bearing Shims

What ever they had when new, will not work the way they did. The reason being being is the amount of filing that has been done, on the part lines, that will leave you short, in the amount of shims, needed. We normally use .032.

If you want the exact amount needed, the only way you can do that is set up each cap on the bare block, with bare caps, that is no babbitt, and measure, up, and down, and side ways and make the hole round with shims, until it is. The caps have to be fit to the block, and not rock, at all.

Now you know how many shims it needs, at this point. When you pour the three caps, they will warp some again. So now clean the babbitt, NO part line metal, and Mic from the part line, to the top of the bolt hole in the cap, then level the caps again, and measure the caps a second time, and if what ever difference, say .003, add that figure to your shim pack amount, and you will have the right amount of shims.


juke joint johnny 03-05-2020 03:49 PM

Re: Engine Bearing Shims

Thanks Herm
Very informative

I asked the question as some engine builders in the UK do not put the shims in just line bore after pouring the mains
I always thought that was a bad idea and now I know why!!

31Cabriolet68-C 03-06-2020 01:26 PM

Re: Engine Bearing Shims

Vince's tutorial/discussion on engine main-bearing shims specifically recommends using steel shims...
Do most Model A parts suppliers offer them?
Would one vendor be better than the others?
Thanks, JB

All times are GMT -5. The time now is 10:30 AM.

Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2021, vBulletin Solutions Inc.