Sent mine to Damper Doctor in CA. Cost about $100 for rebuild with new injected rubber. Been working fine for the past 4 years. Of course, my engine is not for racing, just street.
Did the timing mark on the balancer change around 1975 and a different cover and timing tab show up on the 350? this means that when you put a new balancer on a 74 or older the timing will be wrong. verify the ketway to timing mark . my want to check the timing with a timing light before you change the balancer. then check it after to make sure its the same as the new balancer.
Only difference in timing covers is that the later ones had bolt on timing tabs as opposed to cast in timing tab. Timing scale should be the same. Only variable is the accuracy of the balancer timing mark. Check that with a piston stop. If it is good, set your timing with a light.
Does the small-block damper use the pound-in weight(s) in one or more holes along the perimeter of the damper like the BBB? If so, you'd want to cram the weight(s) from the old damper into the new one, in the same relative location.
I would not change weights,new ones should already be balanced. . I have never changed weights on any balancer changes. As far as changes to timing marks depending on year, 75 added an additional mark for magnetic timing machine.
The damper is neutral balanced, with a bunch of holes equally-spaced around the outside. Buick slams a pin or two into them to "fine tune" the engine (crankshaft) balance on an as-needed basis--number of pins and the location varies with the individual engine. With a pin or two installed, the damper is no longer neutral-balanced, it's mated to the crankshaft so the assembly is balanced. If you don't transfer the pins from the OEM damper to the replacement, you just screwed-up the crank balance. As I recall, they do about the same on the flywheel end by custom-drilling to selectively remove weight, so if you change flywheels, you need to match the new one to the old one (or get the engine properly balanced by a competent professional instead of the half-assed OEM method.)
Does anyone know a company in Canada that rebuilds the harmonic balancer? Don’t want to be screwed if the two postal services lose the one I have. Putting a 72 Buick 350 engine in another car, and no-one seems to be able to help if you cannot provide the VIN. Looked to Original Parts Group and they cannot give any dimensions on the ones they have on the shelf. Anyone deal with that company?
OPGI? Lying dirtbags. INFAMOUS for backorders that take five times as long as they claim, to fulfill. And they sent me postcards advertising the very same product they were totally unable to ship to me, because "their" factory (in Communist China, but it took three months of phone calls to get them to admit that lil' fact) could not produce the thing and have it meet quality standards. I called them every month, and every month they pretended they'd ship it to me in "about a month." NEVER AGAIN. NEVERnevernevernever Again.
Damper dudes is great used them a few times. Use Canada post who transfers to USPS. I've never had and issue and I have spare balancers in Edmonton in case you end up needing another.