21 A rod question

[4tford]

Thanks for the info on the other rods now I am Still sorting rods. Can you tell me if both these rods are 21a/91a rods. Measure pretty much the same. Is the straight one an earlier style??? The one on the right is NOS.

 

[59ab]

I beleive the one on the left is a 91A. As I understand the only difference in the two is what you can see. The extra beef on the big end and the self locking nuts on the bolts is the 21A.
Hope this helps. Eddie

 

[Flathead]

The one on the left is real early, should be dimensionally the same. Not as strong as 21A rod and weight is different, so mixing them will be a balance problem. Early rod will give more clearance for a big stroker, but you trade off strength. Good luck.

 

[Karl Wolf]

21A and 91A look the same... And yes the left rod is dimensionally the same, You would not really want it in your new stroker motor, would you? I could look thru a set of them in the morning and see what the cast number is... Karl

 

[4tford]

Thanks guys, this is what I thought.

 

[flatjack9]

The one on the left is 21 stud, early 38 and back. Definetly not 39.