Anyone know the part number for a Ford '70-'71 timing set? When I replaced the set in my 1980 351M I assumed it was the original one since the nylon teeth were worn and chipped and the chain was very loose (120K miles). I just noticed that there appears to be a part number on the cam gear, D0AE 6256 A. I bought the truck with 80K miles, did the previous owner replace the original with a 0 retarded set from pre-72?

 

Cam sprocket alignment did not change when Ford introduced retarded cam timing in MY1973. When retarded cam timing was introduced in 335-series engines, Ford introduced a new timing set, with narrower sprockets and a 4-plate chain (instead of the original 5-plate chain). The cam timing change was implemented by changing the alignment of the crankshaft keyway with the index gear on the crankshaft sprocket.

All '77-'82 351M/400 truck engines used the original 351C cam timing sprocket (D0AE), with the wider 5-plate chain.

Most 351M/400 truck engines were equipped with a truck-specific crankshaft sprocket (D7TE), which incorporated the retarded cam timing in a wide sprocket.

Some 351M engines used in '78 Broncos and '79 HD pickups used the original, non-retarded crank sprocket (C8SE).

Ford no longer offers a service part replacement for the complete timing set, but you can still get the individual sprockets and chain. The non-retarded crank sprocket service part (C8SZ-6306-A) is obsolete and no longer available.

If you want to eliminate the retarded cam timing on your engine, use a good-quality aftermarket double-roller timing set. Most aftermarket "performance" timing sets have multiple keyways in the crank sprocket, which allow you to set the cam timing you want in 4-to-6 degree increments (advanced, zero, or retarded).

 

Thanks for the info, that makes sense now. I didn't notice a part number on the crank gear but it was dirty and may have been covered. I already replaced it with an Edelbrock double roller set and installed it straight up.