[433lemans]

Originally Posted by Jay S

If the balancing will be done by anyone other than a Pontiac specific shop, it is the safest to neutral balancing it and buying an aftermarket neutral flywheel. I have ran into to many Pontiac’s that are balanced wrong for the factory flywheels. You are not the only person that has thought Pontiac’s are all internally balanced. As Pontiac’s have been built less, I think the issue has gotten worse.

This brings up an important issue for me. I have an assembly that I had done years ago. I can't for the life of me remember which flex plate I included when the machine work was done. I have the factory flex plate that was balanced with another project a long time ago, and I have an aftermarket internal, and an aftermarket external balance flex plate. The shop that did the work used to be reputable but work I had them do more recently led me to believe otherwise. Is there a safe way to go or do I take everything back to a shop? Sorry if I'm taking away from the OP.

[Jay S]

Originally Posted by 433lemans

This brings up an important issue for me. I have an assembly that I had done years ago. I can't for the life of me remember which flex plate I included when the machine work was done. I have the factory flex plate that was balanced with another project a long time ago, and I have an aftermarket internal, and an aftermarket external balance flex plate. The shop that did the work used to be reputable but work I had them do more recently led me to believe otherwise. Is there a safe way to go or do I take everything back to a shop? Sorry if I'm taking away from the OP.

If you sent it with a flywheel and don’t recall which type it was, I think you’re probably out of luck on being able to tell which type it had. I have been around a ton of Pontiac’s that were internal balanced but they used the OEM flywheel thinking it was internal balanced. To be more than just a guess you will probably need to have the crank spun on a balancer again with the correct bob weights. I wouldn’t think it would be very expensive to do though. For neutral balance it does need to be checked with a flywheel. If it comes up being off and needs an adjustment on the back counter weights when spun without the flywheel it was likely balanced for the external flywheel.