Love1955oldsmobile

I have had olds in my blood for over 50 years.

On the first gen engine i hear talk of internal/external balancing but no one really spells out the difference.

When i was a teen i had 2 1956 olds and both had factory air. The harmonic ring came loose on 1956 so i needed to replace the crankshaft pulley. This was before there were companies that did rebuilds.

I had a 1959 pulley that was 4 grove and 1956 were 3 groove. So i mounted the 1959 pulley no problem. Cranked the engine and it was rought to say the least. Took the pulley off and compared the two. The 1959 had a cast in weight. Using a lathe, i cut the weight out remounted the 1959 pulley in the 1956 - problem solved.

I am using a 1958 371 (external balance) inplace of my 1955 324 (internal balance) . I am going to use the 1955 pulley on the 371 as a/c is involved.

So the question is what else is involved in balancing other than the pulley and its counterweight? I will add weight to the 1955 pulley. It looks like an ounce or so will be required by memory.

Details please to document this subject.

Thanks. Ron

Tedd Thompson

Because of the 4 grove pulley I'm not sure(I don't know if they were weighted on a 371 differently than a 59 371). If I'm not mistaken a 59 371 is basically a small block 394 so you are two generations away from the 56 with a pully that is as rare as hens teeth, would be a shame to mess it up. This is just speculation so take it as a wild *** guess at best just to many unknowns and IF the pulley needs to have added weight as it was originally as a 59 371 do you know where it needs to be added and how to attach it so it will be there forever. I've probably made things more confusing than someone who has done this before. I would probably try it as it is now and see how much vibration there is and adjust from there..... Tedd