Model A and B engines

C

Cockshutt Kid

Member
God morning guy's. Last time I mentioned that I got 2 A engines and a B engine. I have them substantially apart, and it looks like the two A's are just cores. The B looks to be fairly good, except that the pistons, rods and oil pump are missing. I have never seen inside a B engine before. My problem is how do I know for sure what I have. I understand that there are two different cranks, and that the one is more desirable than the other. How do I identify which I have? Also I have searched the net, but cannot find what the stock dimensions of the throws and mains would have been to know if this one has been turned. What would the stock bore of the cylinders be? Is the oil pump the same as an A or did it have higher capacity?
Thanks guy's. I appreciate the help. I thought I was a bit of a car guy, but it is amazing how little I know when get into the details of this stuff. A little humbling. Thanks again, Jim.
 
One version of "B" crank looks like a thicker "A" crank, thr other 2 versions have counterweights, one is forged one piece, the other is shrunk on rings, the shrunk on rings are better from a balance standpoint, but worse for grinding rod journals because they have to be moved to grind them

cylinder bore --std A, and B, 3.875" --the stroke is the same for A, and B
A rod 1.498 --main 1.623
B rod 1.874 --main 1.998

The "B" oil pump has a little more flow and works in the A
The B cam is a better cam (if not too worn) and works in the A
B engine blocks like to crack at the exhaust valve seats more so than A blocks
both engines use the same valves and pistons
 
Thanks. The crank that I have does not have any more counterweights . it is ,as you say, the same basic shape as the model A except much heavier. The circular portion next to the throws has been drilled on the perimiter, I assume in an attempt to balance it. I am sure that it is factory. Looks like it might be standard size.
Is there any easy way for me to identify the B oil pump when rummaging around in piles of used parts? Thanks again.
 
Sorry about that. My computer skills showing up again. Would I be able to see the difference in the A and B oil pump externally, or would it have to be dismanteled to notice?
 
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