Fairbanks mag J4b3B

nebken · Nov 20, 2013

I've had several Allis mags J or X 4B3. I ran across a fairbanks type J4B3B. I took it a part and found it had a 35 degree impulse.

Does the extra "B" mean it's 35 instead of 30 degrees?

What does it fit? Will it work on a WD? I know it should be 30. Only being off 5 degrees I would think it would be ok.

Lonnie Smith · Nov 20, 2013

The second B stands for a variation but my paperwork doesn't say what it is, probably the degrees like you said.

ACEd · Nov 23, 2013

As I recall, FM series mags decode as follows

FM - Fairbanks Morse

K = larger, older style with one piece top
J = newer style with top and separate cap
X = similar to J but newer style

4 = 4 cylinders

B = flange mount
A = base mount

3 = Allis Chalmers
4 = Minneapolis Moline
9 = Continental
11 = International
etc

Sorry but Can"t help with the last B

Fairbanks mag J4b3B

nebken

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Lonnie Smith

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ACEd

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