Reply to "Normal engine life"

Peter, IMHO the fastest wearing assembly in the 351-C engine is the OEM timing chain. This is because of the weight of the huge valves and the rpm capability of the 4V engine. With the link-chains you were lucky to get 20,000 miles before the thing was so worn, the cam would jump timing. And both sprockets usually were gone along with the chain. A double-row roller chain NOT made in India or China is a good idea, extends assembly life by maybe 2X and with the new sprockets needed for this different kind of chain, you usually have 3-9 different cam timing slots. As-stock starting in late '72, Ford retarded the cam 4 degrees for smog purposes by retarding the crank sprocket keyway. There are other soft spots in the Cleveland engine design (like the distributor drive gear roll-pin and the stock oil pump driveshaft), but the cam chain is the first place I look. If you're lucky, all this may have been changed by a previous owner.