Does the 425 use the same balancer as any of the other olds engines?

 

Probably not exactly the same. You know how GM did everything....
They reinvented the wheel every year.
A 455 balancer would probably absorb the harmonics just fine.

 

No difference in the crankshafts that would prevent the use of the 455 balancer?

 

I believe the front bolt and threads are different.

 

You should check part numbers, I think the 330 and (65-67) 400 and 425 used the same balancers but the 68 up engines were different and the engines were balanced differently.

 

Balanced differently?

 

I thought there was a difference in the factory balance , internal vs external...?

 

Don't know about different balance on later motors, but any 65-67 V8 balancer will work on a 425. The 64 330 motors have a different timing mark location due to the driver's side water pump inlet. Of course, if you are going to degree the balancer for your motor, then just scribe a new line in the correct location.

 

I thought that 425 had a different weight too. I seem to remember a bolt on weight for the aftermarket ones for 425

 

News to me. The flexplates are the same for all 64-67 motors. I can't imagine that you'd put all the balance mass at one end of the crank - that would set up torsional vibrations in the crank. Note that Fluidamper, ATI, and TCI all show the same balancers as fitting all Olds motors without mention of any removable weight. The Professional Products balancer claims to have a removable weight if you want to use it in an internal balance configuration, but that's a custom build.

 

I wouldn't use a professional products one if it was free.
Like I said I remember seeing a balancer (not a P.P.) with removable weight for an Olds and thought it was for the early engines 64-7.
On here it says by allthe balancers that early 400/425 must be rebalanced to use the regular balancers
http://www.mondellotwister.com/Crankshafts.htm

 

I doubt any of them are still in balance after 40 years. As long as they absorb the shockwaves, and your bearing clearances are ok I wouldn't sweat it. If you are going the performance route, than get a nice Pro-Race or something.

 

Uh-oh there ya go reading Mondello gunk again. None of the 330 cranks I ever had needed to have the timing marks re-done. Maybe I never had a 64 (early) one like Joe said. Having to rebalance the 400-425s were not explained either. I'm afraid I'll need more explanation than that little foot note.

 

I knew I was in dangerous water quoting Mondo. lol
64 330 were different for timing marks, because of the opposite side w/p probably.

 

Thank you. That was exactly my reaction. And you are right, the "re-mark" remark (yeah, I'm too clever for my own good...) only applies to 1964 330s that have the timing tab on the passenger side due to the one-year-only water pump design. Unfortunately Mondello fails to make this distinction.