In the early 80's smogged trucks 300 I6 engines, are the cams retarded? If so, by how much and was it done with the gears or by the cam grind.

Thanks, JB

 

later model 300's have their cams retarded 4 degree the retard is built into the crank gear.

 

Matthew: Thanks for the info. Armed with your knowledge, I got a Cloyes 2764 gear set. Before I did so, i phoned them, and, after looking at the blueprint, assured me that this set is straight up. After I got it, I traced bore and the dotted tooth very carefully, and then put the old gear accurately on top of the tracing. I did three runs, just to make sure: got the same result every time. There are 29 teeth on the crank gear, so each tooth is 12.4 degrees. Sure enough, the new gear is advanced about a third of a tooth, so i can tell you with certainty that, in 1981, the smogged sixes had their cam timing retarded 4 degrees.

Interestingly, the original gear in the truck has 2764 stamped on it. The tooth dot; however, is not in the center of the tooth, but ahead a bit.

If returning the cam to straight up makes as much difference as it did in my 84 460, I will be happy indeed. Hope this info is useful to another shade tree mechanic out there. JB