Small Block Harmonic Balancer Differences

[luke-ao]

So I had a 302 setup for one truck that only needed a single V belt to drive the fan and alternator. I'm switching it over to a two belt system for power steering and alternator for another truck.

I already switched out the water pump for the PS bracket mounts but I just noticed that my single belt HB sits back too far so the pulleys don't line up. Plus one lower pulley uses 3 bolts and the other uses 4. (I was just going to re-drill be before I noticed the alignment problem.)

Their both 28oz imbalance engines, so I assume I can swap out the Harmonic Balancer(?) But another difference I see is the location of the ignition timing pointer, one is on the passenger side of the engine, and one is on the drivers side. I would assume the location of the key-way dictates the location of the timing marks(?)

SO, can I just swap these out?? My guess is yes, but I wanted to run it by you guys first.

[basketcase0302]

"luke-ao"]So I had a 302 setup for one truck that only needed a single V belt to drive the fan and alternator. I'm switching it over to a two belt system for power steering and alternator for another truck.
I already switched out the water pump for the PS bracket mounts but I just noticed that my single belt HB sits back too far so the pulleys don't line up. Plus one lower pulley uses 3 bolts and the other uses 4. (I was just going to re-drill be before I noticed the alignment problem.)
Their both 28oz imbalance engines, so I assume I can swap out the Harmonic Balancer(?) But another difference I see is the location of the ignition timing pointer, one is on the passenger side of the engine, and one is on the drivers side. I would assume the location of the key-way dictates the location of the timing marks(?)
SO, can I just swap these out?? My guess is yes, but I wanted to run it by you guys first.

Yes as i did the same thing in the past on my last build. I can't explain the design of it and the difference between the two, (possibly in the crank holes) but it worked for me. I still have the old timing pointer and water pump from that swap.

[luke-ao]

Thanks.

[Ranchero50]

Pre '70 were three bolt, post '69 were four.

Reverse rotation water pumps use a different bolt pattern as well.

Try to stay in the same generation car and truck and you'll be OK. '64-'69 or '70-'73 or '84 and up serpentine belt. Avoid the emissions years.