I have been fighting a bad miss on my 460 for quite some time. The engine has 2000 miles on it and the ignition system is an all new MSD unit except for the distributor itself. Today, the engine finally quit running while going down the road. When I removed the cap, the rotor would turn almost 90 degrees. I pulled the distributor out only to find that the drive gear was badly worn and missing some teeth! Has anyone experienced this? I can install a new one, but how do I know the same thing wont happen again?

Thanks

 

i had the same thing on my newly built 460. do you have a high volume oil pump? melling claims it's a myth that they wear down dizzy gears. but i searched the net and found a lot of examples of the same problem. i tried the MSD super steel gear. it lasted a little longer but still wore down.
i finely bit the bullet and pulled off my nice freshly installed, leak free oil pan and put in a regular oil pump. i also put on another dizzy gear at the same time. it's been about three months and it's doing good.

 

I do have a high volume oil pump and this may well be the problem. Have you heard anything about the new polymer drive gear that Comp Cams has now? They are supposed to be strong and provide less friction, but I am leary of using a "plastic" gear given my problem...

 

I would also be leary of a plastic gear, no matter what hi-tech name they call it! I have always used the bronze gears as they are almost as strong as the steel ones, but because of bronze's inherent lubricating qualities they really reduce the friction. In addition, because the bronze is slightly softer than the steel cam gear it is being meshed to, the bronze gear will "conform" and wear to "fit" the cam gear, rather than just the two of them grinding each other up. If you distributor gear was worn that bad, and missing teeth, I would definetly check the camshaft gear to see what shape it's in, otherwise the same thing will happen again.

 

I had a bronze gear on my 351W and after about a year, I couldnt get it to time correctly. I tried a lot of different things including replacing my MSD unit and replacing my Pertronix unit. None of which worked. Then I pulled the "dizzy" and found the teeth had been worn down to little knifes. Well, I took the bronze one off, and put on a cast one again. The timing issues were solved. I put on a bronze one for the same reason....My original dist gear had been chewed up and spit out. I figured the same thing about the bronze gear. I figured that if I put the bronze one, it would be soft enough to suck up any misalignment in the cam and all. Well, the cast one now works just fine, and I dont have any problems with racing it and having it drop off around 5500 RPM. Now it spins no problem up to 6500 RPM and runs great.
I would pull the distributor, and turn the motor over by hand looking down the dist hole at the cam gears to see if anything looks out of place. If it looks good, put a cast distributor gear back on and see where you end up. I would deffinatly put a magnet on the oil pan though in case something else happens again though and to catch any and pieces which may be floating around in your oil. Hope this helps.

 

I suppose a lot to do with this problem has to do with the camshaft itself. These are helical cut gears and they do require pretty accurate machining to mesh properly. Unlike a ring and pinion set which are manufactured as a pair and machined to mesh exactly, we are mixing and matching gears from different manufacturers, with cams from different companies. This has to cause a problem eventually!