I have a 72 Duster 340 with matching numbers engine. It needs a rebuild. I was thinking of putting a 4.00 stroker in it. Has any one ever had the assembly balanced with the original 72 dampner? It isa 4sp car.
Thanks, Rod

If your thinking of a 4" stroke then you dont need to check if your current crank is forged(74 340 was
a cast crank so your balancer will be for a cast crank.. just something to think about

Maybe I didn't phrase the question correctly. It is a cast crank 72 and up were cast. I was thinking I should keep the stock balancer to maintain the stock look.

You can use the stock 340 external balanced flywheel and dampener if you want
I built a 340 4 inch forged steel crankshaft build for 9secondphil years ago, I used all neutral balanced stock stuff, his was a 727 car so no flywheel.
I had Automotive Balancing in South Gate do the balancing on that job
Only you, Gene, Bob M and few others would notice the difference in the balancers

You can, but you shouldn't.
Why?
It's 48 years old, and the rubber that does the job is nothing like what the factory put there. It cannot work the same way, and if it shears internally it goes bang.

Factory balancers were marginal pieces when new.
It goes in the .02 $ per pound pile in my garage.

My 72 4 speed crank is forged. My 73 is cast. Are you saying yours has a counter weighted dampner on it now? It will say cast crank 340 only right on the dampner If so you are asking if you can externally balance the new stroker assy. The answer is yes. Do you need to? Depends on the bobweight of the new assy. If its considerably lighter it may balance without the need for the extra weight of the external parts. In this case flywheel and dampner. Using the stock flywheel is probably more of a risk than using the stock dampner as far as a safety concern. As far as using external balance. All 360's, 454 Chevy, Ford SB all use external balance.
Doug

Are you going to use a cast stroker crank? If so, just externally balance it with your oddball 340 damper (if its a factory cast counterweighted 340 damper), as I think its silly to throw mallory metal into a cheap casting anyway. If its a forged stroker, throw a good damper on good parts.

Another course of action to consider....I pulled my number's matching block out of my '70 440-6 stick car and stored it safely in my basement. Then I built a 493" RB with ported Indy EZ's and a solid roller, which is way more fun on the street. If it ever grenades, I won't have lost the number's block.

I seem to remember that Mopar used forge steel cranks in all the 4 speed cars and trucks back then
I have a original1976 400 stick shift motor that had a forged steel crank in it with a stock looking thin dampener with a bunch of balancing holes drill on the back side of it