Oversized O.D. Main Bearings

Dads41SuperDeluxe

Dads41SuperDeluxe

Member
Can anyone confirm what I am hearing from my machinist? He was installing new main bearings in my '41 Sedan Coupe and says that the block and bearing caps have been line-bored 0.015 over original and requires the bearing to be 0.015 larger outside diameter. My existing bearings fit, but replacement bearings are loose. He says that during the war, in order to save a block that had spun a bearing, they would line bore the block/bearing caps and install a bearing that had a larger diameter.

So, for my '41 Sedan Coupe:

1) Is this true?
2) If it is true, does anybody have replacement bearings with larger OD?

Thanks
Len
 
Are there markings on your old bearings to indicate oversize? There usually are, either the oversize dimension or a special part number.
 
Main caps are generally cut down a bit on the cap parting surfaces utilizing a special fixture in a lathe. The amount removed is generally small but it allows the bores to be re-centered & sized back to standard. If they did do it in the past, there may have been some oversize Id bearings at one time but I would doubt they be easy to locate now. I'll never say never on things like this but it might be easier to find another block. It won't hurt to look around a while though. You never know what is still lurking around out there in old parts piles.
 
There was not a part number and any indication that the OD was different. We ordered bearings assuming they would slip right in. Problem is they slip in to easily.

Where can I get a block?
 
Line boring it back to standard would get you into a gear back lash problem. Would need to find under size cam gear then. Best to find another block if bearings can't be found.
 
What size is the crank journals?
Rear main .015 oversize/std 81A 6331 H
.015/ ,010 81A 6331 K
.015/.020 81A 6331 U
.015/.030 81A 6331 V
All the above bearings have length between flanges .010 narrower than stock [stock is 2.095/2.097]

front and centre main bearings with .015 oversize o/d
.020 under crank 81A 6333 P
.030 under crank 81A 6333 Q

Sorry, have no other info on other sizes
 
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Those ERP blocks are still lurking out there. I got bit myself maybe 30 years ago and I never forgot about it. I did finally find some bearings but it took a while, and most people didn't know what I was talking about.
 
BEARINGS CALL GOTHAM AUTO PARTS you will speak to james formley of job lot a great man to deal with he can help 718 878 3699 tell him richard of gas light garage sent you
 
Thanks Richard - no luck with james, but nice guy. Flathead - I'm finding the same thing. My rebuilder is talking about shimming. Anyone tried that?

I'm trying Chuck now
 
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