221 rear main needed, and a question about width

mumpsimus

mumpsimus

Member
The rear main bearing on my motor is OK diameter, but there is a lot of end float on the crankshaft: about 0.025" The bearing is 2.246" wide overall. Does that sound correct, or is the bearing worn on the thrust face by about 0.020"? I don't have another bearing to compare it to.

I've called a few of the shops, but nobody seems to have .040" over main bearings for sale. (crank is ground to 2.360" but 2.400" is standard) Does anybody have a 040 rear main on their shelf? I'll buy the set of all three main bearings if needed, but the other two are OK in my motor.

thanks!
Pete
 
Std length is 2.249" -2,251". Ford did manufacture some rear mains 0.015" longer...unfortunately I have no part number for this particular bearing.
If you can only source std length 0.040" rear main bearings, what I have done occasionally over the years in this situation is to build up the flanges with babbit and machine back to the size required. It can be done! Good luck with your hunt
 
Brian said:
Std length is 2.249" -2,251". Ford did manufacture some rear mains 0.015" longer...unfortunately I have no part number for this particular bearing.
If you can only source std length 0.040" rear main bearings, what I have done occasionally over the years in this situation is to build up the flanges with babbit and machine back to the size required. It can be done! Good luck with your hunt
Click to expand...


Sounds like my bearing is standard length within a few thou. So it must be the crank that has worn to allow so much float?


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Brian said:
Std length is 2.249" -2,251". Ford did manufacture some rear mains 0.015" longer...unfortunately I have no part number for this particular bearing.
If you can only source std length 0.040" rear main bearings, what I have done occasionally over the years in this situation is to build up the flanges with babbit and machine back to the size required. It can be done! Good luck with your hunt
Click to expand...


Hi Brian. The crank is 2.275” wide between the oil slinger and cheek of the bobweight. That slinger isn’t removable is it? Wishful thinking!

It sounds like my crank wore 0.025” for some reason. I would have expected the bearing to wear, not the crank.

What happens if the crank is allowed to have .025” of end float? That seems like trouble. Possibly the gears to the cam would wear?

I don’t want to buy a new crankshaft, so I’ll keep thinking about this.


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More likely, whoever ground the crankshaft, widened the thrust faces with the edge of the wheel. You definitely do not want to reassemble the engine with .025" end float! Like I've previously said, Ford did supply bearings .015" longer in some sizes, but I cannot find a part number for .040". Barnfind has .040" bearings, possibly he has the .015" over length version too, however, you'll still have excessive end float. So, either build up the thrust faces of the new bearings and re-machine to suit, build up and re-machine the crankshaft- many $$$$$, or find another crankshaft. If I were you, I'd use option 3, try and find a crankshaft with closer to std sized journals
 
Brian said:
More likely, whoever ground the crankshaft, widened the thrust faces with the edge of the wheel. You definitely do not want to reassemble the engine with .025" end float! Like I've previously said, Ford did supply bearings .015" longer in some sizes, but I cannot find a part number for .040". Barnfind has .040" bearings, possibly he has the .015" over length version too, however, you'll still have excessive end float. So, either build up the thrust faces of the new bearings and re-machine to suit, build up and re-machine the crankshaft- many $$$$$, or find another crankshaft. If I were you, I'd use option 3, try and find a crankshaft with closer to std sized journals
Click to expand...


I thought about it for a quick minute, then took the main bearing to a local friend who is a pre1916 car machinist. He’s adding babbit to the thrust face tomorrow. Maybe a previous owner held the clutch in a lot at stoplights which loaded up that bearing and wore the slinger face on the crank. My buddy has done several bearings like this previously, so I’m happy to follow your advice and his. Fingers crossed that I’ll be reassembling the motor next week.


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