Balance Problems...Vibration......

340? cast or steel crank? internal or externally balanced? start with casting #'s on block ( date code ) i have seen the inner hub spin in the balancer. is it really strange when you check the timing? ok stupid question time have you doubled checked the plug wires to make sure you don't have one crossed or out of order. you can get a fluid dampner from jegs , summit , or whereever.