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Did OEM use odd ball size rod bearings.....440


FBBO Gold Member
FBBO Gold Member
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10:36 AM
Feb 29, 2020
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Heart of Dixie.....
Pulled a 1974 cast crank engine apart for a rebuild. Pretty sure it had not been into before now. In measuring the crank main journals they all came in at 2.750 or 2.749 with 2.750 being dead stock. But the rod journals came in at 2.373 or 2.374 with 2.380 being dead stock. Would the company have used something like .005 or .006 oversize bearing as I don t think the rods could have been worn 5 or 6 k and mains have no more than 1k wear....that does not add up. Now in searching bearing sizes available I find all the standards, 10,20,30,40 and 50k. Only odd sizes were .001 and .011. It appears that even though the crank is in great shape with little wear it will need the rods reground as there are no bearing available in that size today.....opinions....thanks.....
Any original engine I took apart had date codes on the bearings. New bearings have the same date codes. See if the dates line up with the engine dates. If they do then it came that way.
The R/T Boy is correct 2.375.
For foggy memory's sake I just looked at my notes from the OEM 440 I tore down, factory .010/.010 under crank and the rod journals checked out at 2.365.
The factories are always looking to save money, scrapping engine components would be a loss of profit, hence, a couple bearings to save a crank.
Check your information source. Those journals are standard and are fine.
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Usually Chrysler stamped the block pad with a symbol when a crank was cut at the factory undersize.
Check a factory service manual for the symbol meanings.
Ok, thanks, good info. I will look at the original bearings for the date code. The book I used for the journal sizes is How to Rebuild your BB Mopar. So, will check some other sources to see if indeed they list 2.375 as stock journals. Don t think I have a service manual that show stamped engine symbols, but will investigate that.
When my Dad helped me rebuild my first cars engine, a 327, Dad said the crank looks good. We put it back in using stock size bearing . Had a terrible knock. Tore it back apart and then took the crank to a machinist . He said it look good but in checking, it had one main journal cut .010 under. I remember him saying that was not unusual for Chevys...he did see that fairly often.
I have had a hemi and a 440 with a Maltese cross on the ID pad.......the both had not standard size rod bearings...I think Chrysler used those on cranks they screwed up.
Thanks all for the updates, y'all were correct. I got a factory Chrysler service manual and as y'all stated , rod journals are factory at 2.375. That is the second major mistake I found in the "How to Rebuild your Mopar Big Block" an HP book, seems somebody would have caught that BEFORE going to press. Also had factory bearing as they were date coded at 11-74. Just waiting on my machine shop now.....
Be aware that your '74 has a different center main bearing than earlier.
If you have a maltese cross as said earlier the crank counter will be stamped with unsized journals. This crank is -.001 on main5 and rods 5,6,7 and 8.
Be aware that your '74 has a different center main bearing than earlier.
What is the difference Dip, I noticed when ordering bearing they were listing different center bearing sizes. I just assumed it had to do with the flange widths... Is the 74 bigger or smaller....thanks...
The later bearings have a larger thrust bearing face, and a corresponding relief in the block and main cap. Earlier bearings can be used in your block, but the later bearings cant be used in an early block.