Harmonic Balancer interchange

[Justin V]

I have a 79 350 that has a bad balancer. I also have a 90 350 that has a good balancer. The parts store says they are not the same. I have both off and see no discernable difference, except the timing mark, because the 79 one is bad, spun the rubber. Can I use the 90 one on the 79? Anyone done this? Parts store listings showed one from 78 to 86, and one from 87 up to 95 I think.

 

[pblaze725]

You could just install the other balancer sure it would work if you were in a survival situation and you had to get out.
The harmonic balancer is designed to work best with that specific engine.
Obviously , like you mentioned is the timing mark is off so it's not correct.
What about the weight? Do they weigh exactly the same?

I ran an incorrect harmonic balancer for a little bit once when I was in a bind.
Sure it mounted and had a smooth vibration & only flew off a few times but it got me home so I could put the correct one one.
My advise is to get the correct part and don't risk it.

 

[diesel4me]

The only externally balanced engines Chevy had up until 1986 are the 400 small block and 454's,they have counterbalance weights on the balancer and flywheel or flex plate..after that I do not know if they decided to change the small blocks balancing and if a later balancer would fit and work on the older 2 piece rear main engines or not..

There are probably 20+ different balancers as far as diameter,timing marks,etc,so it would make sense to use the one listed for your particular engine..but I suppose many would fit and work along with the proper timing mark tab...

 

[Blue85]

Can you swap the timing tab from the newer engine as well? I don't know if it's "OK" to swap them, but sooner or later you'll want to read timing. You can also cut a new groove as a timing mark or put timing tape on it (which has the added bonus of not needing a dial-ahead timing light). I've had timing tape on my balancer for many years with no deterioration. The engine was swapped in before I bought it and the marks were off - I assume it had been some situation like this.

 

[JoshHefnerX]

There's 2 sets of timing tabs and corresponding timing marks on the balancer. Make sure they're the same. May be why parts store has them as different.

 

[Justin V]

I do have a TDC tool, the kind you screw into the spark plug hole. I could locate TDC and mark a new timing line. Seems like more work than it is worth though. 50 bucks for one from Napa or a bunch of time trying to adapt one from the later engine, I think I'll take the 50 bucks route. Thanks for the responses fellas.