I have a '71 360 in my '74 'Cuda that I rebuilt last year and has been running since this fall. The crank was sent out for machining and a good going over by professionals. I have a 650 double pumper on top and a .454/.454 cam in it. It runs well and idles nicely... however once I get out on the road and punch it, the whole car gets shaking. At about 3500 rpm it really starts rattling and the pistol grip starts shaking like crazy.... Its annoying enough that it makes me want to stay within 20 mph of the speed limit... The harmonic balancer is the one that came with the motor and hasn't been touched. Im wondering if its not balanced anymore since the crank was machined and if that is the problem. There is also an aftermarket Vintage Air air conditioning system on the engine and a cast iron pulley that bolts onto the pulley slot on the balancer. Im wondering if that has some thing to do with it. Any ideas?
