[Dave in MN]

Originally Posted by Peter J

Hey Guys,

Originally Posted by Peter J

Just finished putting my B engine back together with the following new parts installed and adjusted to spec. New pistons, rings, rods and pins and ground crank. Valve springs also new.
It was getting really tight especially with the rods down to 001.5. My main concern is that I have little if any side to side clearance with the new rods at the journals. I don't want to put the thing back in the car until I at least get it to turn over with the starter (which I can't).

Thanks for any advice,
Pete

If your bearing to journal fit is to tight it may be limiting your ability to slide the rod back and forth to verify you have side clearance. There is nothing wrong with about .010" side clearance on the rods...which you can see. Try loosening the cap and see if you can detect clearance by pushing the rod sideways on the journal. No side-clearance is… not good, the oil from the dipper must have a path through the bearing to properly cool the assembly and refresh the lubricant. How did you verify the .0015" bearing to journal clearance? If you used Plastigage you may be to tight. Unless you have used this product many times, you may be getting a false indication of your clearances. I have used a lot of it and it will often "lie" with babbitt bearings. I have been won over to using the tin foil method of checking clearances with babbitt bearings. Basically, you place .0015" of aluminum foil in the bearing and try to turn the engine over, if it sticks it's to tight. If it creates a bit of drag, it is probably correct. If it spins freely, remove a single lam. from the shim pack and check the felt turning resistance...repeat until you feel resistance or it locks up. If you have further questions...PM me and I will try to answer your specific questions. There is a good video produced by the Diablo Model A Club regarding adjusting your babbitt bearings. It is available from most Model A Parts suppliers...it is worth getting it. This video shows the use of tin foil and Plastigage. Addition to original post: Herm advises to use oil with Plastigage in a later post...I also use 30 weight oil with babbitt bearings and inserts while taking the readings, but check the use instructions provided in each box. (scan of the instructions in the attachment) The instructions do not indicate that oil should be used. Thus the continuing controversy...To oil, or not to oil, that is the question: