I’m trying to rebuild an extra model a engine I have. Everything seems to be in pretty good shape except the main bearing caps. They appear pretty worn. There were no shims. Does anyone make pre babbitted caps I could purchase and then use something like Timesaver to work in the caps or do I need to have the bearings repoured and line bored. As I said it’s an extra engine and I’m just doing it for something to keep me busy.
Bearing caps
- Thread starter Magoo2
- Start date
Gary WA
Well-known member
I have known Model A people, get caps that were good from swap meets or motors, and doing minor adjustments to the caps. and were successful. And others fit with proper shims. It can be done. That's my take. Unless you find an engine builder that has spare caps,but as far as I know none that you can purchase from vendors.Might check your local clubs, they may have some not being used.
Jack Shaft
BANNED
Yes ford mechanics fit bearings.Timesaver works well especially if its high speed babbit.Ive seen some you can fit with a sharp knife.
Jim Brierley
Well-known member
If the bearing material is good, you can "file" the caps to decrease clearance. Sandpaper or emery cloth on a very flat surface works well. I recommend using plastigage along the full length of the bearing to insure proper clearance along the whole length of the bearing.
redmodelt
Well-known member
I done the cap replacement on my Model T using just repored caps, but that was before I knew what I know now. That engine lasted may years and miles.
That being said, because of crankshaft flex the babbitt in the center main gets more worn in the block then the 1 and 3 so you may not get a good fit. The other thing would be, offset. The replacement/used caps may not be bored the same so may have an offset to the ones in the block. If this is just to practice, go for it. Use it as a learning experience on fitting the crank.
In the Model T days, even with the KR Wilson setup, you could get the caps from Ford that were not bored. You would then poured the babbitt in the block and bore them both at the same time.
That being said, because of crankshaft flex the babbitt in the center main gets more worn in the block then the 1 and 3 so you may not get a good fit. The other thing would be, offset. The replacement/used caps may not be bored the same so may have an offset to the ones in the block. If this is just to practice, go for it. Use it as a learning experience on fitting the crank.
In the Model T days, even with the KR Wilson setup, you could get the caps from Ford that were not bored. You would then poured the babbitt in the block and bore them both at the same time.
Bob Bidonde
Well-known member
I have carved main bearings to fit foreign caps, and when the babbitts in the block are out of round, it is an iterative chore with many trial fits.
If the center main bearing is wornout, the crankshaft likely needs straightening before any bearing work is done, so salvaging main bearings is not practical.
Another concern is the thrust face on the rear main bearing. If it is not possible to get the crankshaft axial play within 0.010", again it is not practical to salvage the main bearings.
If the center main bearing is wornout, the crankshaft likely needs straightening before any bearing work is done, so salvaging main bearings is not practical.
Another concern is the thrust face on the rear main bearing. If it is not possible to get the crankshaft axial play within 0.010", again it is not practical to salvage the main bearings.