If any 283s came from the factory with a bolt-on damper, I'm not aware of it, and I started doing engine work in 1958. They're a press fit. The first engines that came with damper bolts came out in the mid to late 1970s, mostly late model 327s and 350s. If you have a 283 with a bolt in the crankshaft snout, it has been installed (and probably overtorqued) by some shade tree wrench jockey long after it left the factory. The balancer/damper is keyed to the crankshaft, so it cannot possibly spin out of position. The outer ring of the balancer can lose its grip on the rubber damper that holds the two pieces in alignment, and the timing mark can move that way, but the center hub cannot move unless the Woodruff key shears off. I don't think I've ever seen that happen in 60+ years of making a living fixing everything that rolls, floats, or flies, and 30+ years of teaching the trade.
Jerry
