motor balancing question

[72blazerguy]

383 stroker in my 71 blazer - externally balanced and want to upgrade the v-belt system to a newer style v-belt system with the alternator on the passenger side. As I was pulling the accessories, noticed that the main pulley has been balanced. My understanding of external balancing is that the flex plat and harmonic balancer are balanced, but nobody mentions the main pulley.

Will I put the motor out of balance by switching the pulley to a non-balanced pulley? Is this typical for an externally balanced motor? I thought the pulleys would be zero balanced.

 

[4X4HIGH]

That is a cast iron pulley (pretty rare) and that pulley was balanced from the factory and has nothing to do with the engine balancing. You can swap pulleys without any issues.

 

[72blazerguy]

Thanks, confirms what I thought. I didn't remember taking it to the machine shop where they built the motor, but its been a few years.