My dad's got an 87 F-350 w/carb'd 460. About a year ago he bought a replacement motor from Autozone. With less than 20,000 on the rebuilt, (yeah right), long block, it quit running. He realized that the valves on the number 1 and number 5 cylinders were not opening. After pulling down the top end, he found that the lifters and cam were destroyed! Some of the lifters were completely rounded off and a few even had holes punched right through the bottom. Also the distributor drive gear had taken a beating that left it missing a few teeth. The "pad" inside the block that the drive gear sits on when you install the dist. had grooves cut into it as well. No clue what could have caused all this destruction, (the cam obviously wasn't replaced in the longblock because it said "Ford" on it, but I'm sure they would have replaced the lifters.)
Anyway, he installed a new cam and lifter kit and a new dist. When we cranked the motor and had it running at 2K for the cam break-in, the dist. was shaking but quit after a few seconds. However, within a few minutes, a big backfire and it quit. We pulled the dist. and again the gears were ground into and busted off. What could be causing this? Is it possible that Ford used different dists. for different years in this engine? Or that the "pad" inside the block I mentioned earlier being chewed up could cause the problem? The dists. he's been using have had cast iron gears, I know that steel and cast iron gears are not interchangeable, but how do you tell which one you need?
Anyway this project is starting to get expensive for him and I just thought someone in the forums may have some suggestions...thanks.

 

I would venture to say the cam bearings and thrust washer are gone also, cause it sounds like the cam is walking all over the place to have chewed up the dist. gear that fast.
When I installed an aftermarket distibutor from Performance Distibutors (DUI) there was supposed to be like 60 thousands between the bottom of the gear and the deck below it. I guess the oiling to the dist. gear is not that great so they suggest to take the lifter oiling galley plug out and have a .0025 hole drilled in it to aid in the oiling to the gear.

 

Did you pull the oil pump driveshaft and make sure it wasn't twisted or bent?

 

Honestly I hadn't thought to check it, (duh). Actually he, (my dad), called me today and asked if I thought that the oil pump might have locked up and caused this. So we'll investigate the pump and shaft next...

As for the thrust washer...It's funny you should mention it. The first thing I said when I saw the damage was: "Where's the thrust washer?" Not only did it not have one, but the guy at the machine shop in town said that 460's didn't use them. The whole time I, (looking like an idiot), swore that I remembered taking one out of my 460!!! I'll research this as I strongly believe the cam is walking around too much grinding the lifters and all the way it has. Guess this means the cam bearings are probably shot too huh? What about the "pad" inside the block where the dist. drive gear sits? If it's all chewed up is the block junk or can a machine shop repair it -- or does it even matter?

Anyway thanks for the info...

 

big red hi. I am having the same problem with my 460 eating teeth on the dist . did you find anything out? and how bout a thrust washer or plate or bearring, do they have it in the 460??
Thanks.
Troy

 

Actually, we did find the reason for the problem. It turns out the guy at the parts house had not once, but twice given my dad a distributor for a 351w. I took an old 460 dist. up there and that's when we noticed that the gear on his was so much smaller, hence, not making good contact with the cam gear and breaking teeth. As for the thrust plate, I was calling it a thrust "washer" and the guy at the machine shop thought I meant an actual washer that goes between the thrust plate and the front of the cam as seen in some chevy's, (pardon my language - lol). I'm sure you know this, but, in case I confused anyone in the posts above when I had a brain fart and called it a "washer"...The thrust plate has two bolts that thread into the front of the block and hold the cam in. It also has oil grooves cut into the front side to allow oil in between it and the timing gear. The timing gear obviously goes in front of the plate, but about 1/4 inch of it goes through the center and bolts into the cam, drawing it, (the cam), up against the back side of the plate. This keeps the cam and timing gear from "walking" back and forth. That's it! There is no other washer that goes in there. We installed the new, correct, dist., new cam and lifters, (still haven't figured out what ruined them...I assume whoever did the rebuild reused them and didn't put them back in their proper holes...), and new timing set and a new oil pump drive shaft just to be safe and haven't had any problems since. The deck under the dist inside the block is still chewed up but doesn't seem to have any effect on it's operation. Dad has his truck on the road again and says it runs great!

As for your problem, did you recently replace the dist? Assuming that they gave you the right distributor, are you sure that they gave you the one with the correct gear? I don't know why, but some have cast iron gears and some have steel gears, and they are not interchangeable. A steel gear will be fairly smooth around the top and will have horizontal "hash marks" around the teeth. A cast iron gear will have a rough finish around the top, (like on the side of an engine block), and won't have these "hash marks". I'm not sure what'll happen if you try to interchange them, I just know that they aren't.

 

Thanks.
We are looking into a diff. possibility. 1 or both things are known to cause our problem also - 1 the new dist. gear is a couple of thousanths longer thus rides on the block were it engages the oil pump 2- the oil pump is a hi vol /pressure pump = a lot of restriction on the dist. gear causing the teeth to go zip.
Ill double check my dist. though just to make sure its for my motor.
Troy S

 

Sounds like you have the 351 dist too. If the cam isn't walking and the chain is good and all else fails, you can use a brass gear. It won't tear up anything else but itself...

 

Thanks, I just did the shot gun approch and replaced the dist. w/t a msd ready to run dist. ( real cool) and the oil pump to make sure the pump was not a hi vol. or presssure pump. My engine rebuilder looked at my old dist and said it was a little stiff in the rotation, some times the dist might try to seze up when they get warm. thus i took the shotgun approch. so far it is working good.

 

put in a new 400 in an 81 way back it cleaned the teeth within a hundred miles.this was a new block not rebuilt.i couldnt even begin to figure out what happened.tried another dist, and no more trouble.i did have the right dist,first time.i have wondered about it ever since.i thought i was the only one.