The Babbitt broke on my old rods and I am going to buy new ones but don't have a lot of money to spend but on the crank where the rods bolt on measure different from outside to the center the center measures 1.239 and the outside measures 1.234 would it be fine to get a rod that is .020 undersized and shim it till its right I don't have the money for a new crank and was wondering if this will work but on the pistons they say 0025us on them but it might be a os on the end can't make it out but I think they are standerd bore would a set of standerd rings be fine to put on these my name is craig and I'm new to model t's and any help would be appreciated if you need it my email is email@example.com
Get a set of .010" undersized rods and fit them to your crank. .020" will be too small given the measurements you have stated. It is always easier to make rod bearing size smaller than larger. Standard piston rings will work just fine on your .0025" oversize pistons.
If I get .020 undersized and shim them to fit wouldn't it make it easier the next time I have to do it because all I would have to do is take some shims out instead of filing the cap down I don't know if it makes a difference but on one of the measurements I got 1.232
Craig, I don't see how you can have measurements like that and not have a flat crank.
Did you check at 1/4 turns?
Are all the rod Pins alike?
What do you mean by a flat crank but I didn't check it at 1/4 turns. If you look at the crank where the rods bolt on the center is bigger around then the outsides
What do you mean by rod pins
Craig, the pin Herm Kohnke is referring to is the crankshaft pin or journal, the offset bearing surface of the crankshaft the rod bolts to. The pin wears in an engine mostly because of the combustion forcing the piston and rod down creating a flat side on the journal. This makes the pin or journal egg shaped. This is why you need to check the journal not only from side to side but rotate it so that your are checking it every 90 degrees around the journal. If your crankshaft pin or journal is .002 or more out of round then new rod bearing will slap down on the journal every time that cylinder fires. So no matter how close you fit the rod in the beginning, it's life will be short lived. But in the same breath, let me tell you I have heard of old timers back in the day putting a peace of leather in the rod in place of the Babbitt and driving for a long time so go figure.
Bob I have tried the leather bearing on my T which I use as a daily driver. I does work I did about 27 miles before I changed it out.