Can't figure out why I continue to burn up dist gears. I have spent 4k building my 69 351w and it went good. Everything in it is new, about the only thing I reused is the oil pan and the rocker covers. Drove it for 2 months and sheared a dist pin. Put in a new pin and it broke again the next day. Went as far as a new dist, oil pump and shaft. Drove good again for about a month and it ate the gear again. What am I missing that could be causing this?

 

What type of cam is in the motor. Mismatch between cam gear and dizzy gear can cause damage.

 

+1 are you running a roller cam or something

 

It's just a regular Isky hydraulic, 264? recomended by machine shop.

 

Are you losing the gear itself or shearing off the pin? If it is the pin, how easy does the distributor itself spin?

 

The first time, it sheared the pin. Second time, it took some teeth with it. This time it totally ate up the teeth, pin still intact. I'm ready to just get the old "for sale" sign out and be done with it. This is my daily driver and i can't afford this crap anymore. I haven't even looked at the cam gear yet but, thinking by the looks of this gear, a new cam will be in order. It has a new distributor with a pertronixs unit so it spins very easily. no resistance at all. I opened up the old oil pump too and found nothing to cause problems.

 

Sounds like it could be the material the distributor gear is made of. I can't remember which material ie. bronze, steel etc. is recommended for which cam but I am sure others here know much more than I. I would be worried about possible damage to the engine at this point unfortunatly with all the metal from the gears floating around in there.

 

+1, it's probably the wrong material gear.

 

How about the oil pump?
Something in there?
Pleasure relief not relieving?
Did you "shim" the pressure relief for more pressure?
Remember, the cam turns the distributor which is usually easy to turn unless there is a mechanical interference, but that would leave you some destructive clues. Then the dist. turns the oil pump, almost always very hard to turn, are you following me?

 

The material needs to be right, but also cam and dizzy gear thrust need to be set right as well. If the pump jams up that could cause a problem, but more than likely the drive shaft would snap before the gears grenaded.