Pulley Damage

[Overkill-F1]

I was wondering what in the world would cause this damage to the key & the keyway in the front pulley?
The key really widened the keyway!
I have a replacement pulley and it just slips on the front of the crankshaft with .006" clearance. Both pulleys fit loosely.
The front portion of the crank looks ok, the keyway is good here too.

Does anyone know what the diameter of the crank should be there?

Original pulley C8BA-6312-B, the replacement I found is C8BA-6312-A.

'52 F1, C1BA/8RT, 239
...Terry

 

[Ross F-1]

Was the bolt tight?

 

[cmbrucew]

The keyway can be rebroached but if it is loose on the shaft replace it.
Bruce

 

[Overkill-F1]

Was the bolt tight?

Ross, I took it apart a long time ago, so I'm not sure. It makes sense that a loose bolt could be the cause of the damage.
I wonder about the loose fit of the replacement pulley I have.
...Terry

 

[Binx]

Keep in mind your motor's internals or externals (flywheel/clutch) may be out of balance. Shearing a pulley is a sign.

Lonnie

 

[Ronnieroadster]

Crank snout diameter is 1-5/16

 

[Overkill-F1]

Keep in mind your motor's internals or externals (flywheel/clutch) may be out of balance. Shearing a pulley is a sign.

Lonnie

Thanks Lonnie, good advice, I will have them balanced when they resurface the flywheel.

Crank snout diameter is 1-5/16

Thank you Ronnie, 1 5/16 = 1.3125", my snout measures 1.3105 'ish (I got to get a more accurate micrometer over 1")
...Terry