460 w/snapped camshaft
Hi! I have a 77 F250 w/ 460 4bbl with the C6 trans. I bought it about a year ago to use for hauling my car trailer. It did the job in spectacular fashion, for about a month, then started to have some drivability issues, mainly, it was eating ignition modules.
I have run and still do run the HEI conversions in my 69 Galaxy and 53 F100 with 390 4bbl and 289 4bbls' respectively without issue for years, so I made the jump with the 460.
It ran better than ever, started better, got better mileage etc, but occasionally I would get what I thought was a vacuum leak squealing noise, actually more of a whistling sound, but I couldn't track it, because it only happened at speed, as soon as I let off the throttle, it went away.
I replaced all the vacuum hoses, no effect. I replaced the base plate gasket, same result.
I was just about to park the truck in frustration and ride the Harley to work instead, when it parked itself. Driving home from work, about a mile from the house, (The motor was just purring, no squeal at the time) when the truck bucked, HARD, the motor back fired through the exhaust once, then started to run REALLY poorly. I figured it had seized a lifter or broke a rocker or bent a push rod or two or four by the way it ran. I pulled over, popped the hood and listened to it. It had a slight top end knock, good oil pressure, wasn't hot, so I limped it home.
I pulled the valve covers, and fired it up. Sure enough, the rear 4 rockers weren't moving.
I can only assume that, because the lifters move freely when I pulled the push rods, that the camshaft has snapped.
My question is, could the distributor have caused a starvation, or is it just coincidence? The truck served as a farm truck for most of it's life, so the oil was kinda dirty when I bought it. I changed it several times, replacing the filter at 500 mile intervals for the first 3k miles and the oil at 1K for the first 6k. It all looked pretty good. Even under the valve covers looked fairly clean, considering the truck has 114k miles on it.
When I rebuild the motor, I don't want to kill it by re-using the same HEI if that is the problem.
Thanks for any ideas or...