Hey so Ive got a 79 Bronco with a 85 351W swapped in. It was a rebuilt motor (from a prof. shop) when I got it in 2012 or so and swapped it in. Since about Last summer I have started shearing the cam gear pin on the distributor. In the last three months or less I've gone through about 8 including the gear itself being ground down. I originally had an HEI distributor which I replaced with a stock brand new Ford, and it still did it. Then replaced the gear with a bronze gear and it still did it. Then replaced the oil pump and pickup tube and it still did it. Doesn't matter if I'm driving up hill down hill or idling it will still shear a pin almost every two days. Oil pressure reads about 45-60 so I don't think the cam is seizing but I have run out of ideas. Anyone got any clue? If i can't get it right motor and trans are coming out and being set on fire Any help would be greatly appreciated

 

Since shearing the pin is most likely caused by excessive loading, any chance that you have a dimensional issue with oil pump drive or distributor itself? Like something too long and getting jammed down, such that it will turn only with a lot of effort?

It's not like you can just turn something by hand to check when it is installed, so other than some critical measurements against a standard, or other known-correct parts to swap in and try, I don't have any bright ideas.

 

I had one issue with the pump driveshaft where it was bent at a 45 about an inch and a half from the bottom but replaced it and it fits down in nicely with no struggles

 

To shear that pin, it takes some power, cant see it being anything with the distributor. Since you did the oil pump and shaft, what's left? Is the cam walking? I know of people who had to use a cam button (little bronze spacer that holds the cam against the cover, I can see that happening. What bent the first oil drive rod? Can the cam have a defect when they machined the drive for the distributor. Let me ask around and see if anyone in the shop has had a problem like this.

 

I haven't messed with the cam at all. If it came to doing that I'd just as soon replace the motor. It's always had issues since I got it from the rebuild shop and they refuse to warranty it