difference in harmonic balancer bolt sizes?

[buffblazer]

im swapping in a 69-79 gen 350 and my old motor is a 86 350 well i was just going to use my existing balancer and bolt but it wont thread in. now the previous owner said the threads may have been messed up from when he pulled the balancer off, but before i go and start tapping and re threading i was wondering if there was a size difference in the bolts over the years. thanks.

 

[4X4HIGH]

Same size hole for all SBC engines (7/16-20)

 

[buffblazer]

dang i was afraid you would say that. any possibility a aftermarket crank would have a different size hole or do i just need to accept that the threads are messed up and i need to figure out if i can salvage it.

 

[Slapperbar]

All the same thread.

 

[Mike D]

Just run a #2 7/16 - 20 tap to repair the bad thread. In my opinion, usually the first two threads are boogered, preventing the bolt from starting.

 

[pauly383]

If you went and got a 1966 or older chevy smallblock , you wouldn't need a bolt , those cranks aren't even drilled

 

[buffblazer]

Just run a #2 7/16 - 20 tap to repair the bad thread. In my opinion, usually the first two threads are boogered, preventing the bolt from starting.

ok good i will try that and see if it will work