Rear Main Bearing Cap

[Jerry Kzoo]

I have a spare engine that I thought I would disassemble and try to get running. It appears to be in very good shape with pistons .080 over and valves in good shape. My concern came when I looked at the rear main cap. It has a shorter flange for the bolts holding it on and as a result needed 5/8" spacers(larger nuts) put in to fill the gap to get the castle nut high enough to engage the cotter pin hole. Has anyone seen one of these before? I would like to reuse this as the babbit appears fresh and not run before since it was done.

Thanks, Jerry

[DaWizard]

Jerry, I have a stock rear main cap here and just measured the mounting boss and it is just over ½" (.560). How about you measure the thickness of yours and compare it, I am thinking you might have longer bolts than required, or a cap that is not for that engine because if it needed a 5/8 spacer to get the nut to the hole, the mounting flange would be waaaay too thin.

Since my engine is all together, maybe someone else can come up with the correct bolt length.

[Rowdy]

There were 3 different rear main caps used on the Model A. The later one was thicker where the bolts go through. I sent Vince a very early forged main cap for use on making a page on his site. I have not looked to see if the page is up yet, but know he had some work to do to it to make it presentable for the page. Rod

[George Miller]

That is a early 28 cap. they were forged, very strong cap. later ones were a casting ,had to be thicker to be strong enough.

It would be nice if you could find some nice spacers instead of nuts. Better yet why not use the shorter bolts like were on the cap originally.

[Jerry Kzoo]

Unfortunately, the motor has a 1929 number on it and the bolts from the early cap are not with it. It does have the smaller tube to drain oil back to the pan.

[DaWizard]

Hey Jerry, while you have that cap off, be sure to check out the article here https://www.vintagefordforum.com/for...n-oil-leak-fix and do as the man said. I have done it with GREAT success!!

This is a fix I would recommend, and will be doing on at least 2 other club members rear mains. It WORKS!!

Since I am a machinist I did a wee bit more precise than the author of the article, but if you have the basic tools he used and don't get too carried away with the grinding, you can make it work too.

[Rowdy]

All 3 styles of caps. One on the left is the early forged cap. One in the middle is the later 28 cast cap. One on right is the later cast cap. Rod

[Rowdy]

I may have the shorter bolts, but will be Friday at the earliest before I can look. Rod

[Jerry Kzoo]

Rod, thanks for posting the pictures and also thanks for checking on the bolts. The bolt hole flange is about .550" vs. the later caps that have 1.110" flange. The only difference from your picture that I see is that the web from the bolt hole back to the oil slinger area is on the cap I have, but on yours it is cut out some.

[Rowdy]

Jerry, tried to make it to that building at the farm today and with all of the rain we have had there is too much mud to get there. Supposed to be warmer and much drier the next few days. Will try again Sunday afternoon on my way to work. Rod

[Rowdy]

Jerry. Did not find them at the farm. I know I should have 3 sets somewhere. Will continue to look. Rod

[Jerry Kzoo]

Thanks Rod for checking. I still have it apart doing cleaning inside and out. Hope to put on a test stand some day and use as a spare.