Distributor Gear Sheared Teeth

[Chad E532]

Well yesterday was the first trip out with my newly freshened engine. During the rebuild I noticed some wear on the MSD bronze distributor gear I was running so I opted to try the Comp Cams composite gear that claimed longer life.
Pulled into the water box after and just started to get the tires spinning and the engine just quit, pushed it back and got a tow back to my trailer. Pulled the distributor out to find only 4 teeth left on it and the missing ones are sheared off right at the base of the tooth. In my early failure analysis I can only see two possible ways for the gear to lose it's teeth. First would be for the oil pump to lock up or to spin over hard enough to create more loading than the gear could handle and the other would be for some interference between the cap and rotor. When I got home I was able to turn the oil pump fine by hand with my pump primer setup and the cap and rotor look fine.
The only thing I can think of is that these gears will not work with high volume/pressure pumps like the HV55 that I am running. Needless to say I am going back to bronze after I pull the engine back out and find all the missing teeth in the oil pan.
Anyone else had problems with these composite gears?
Thanks,
Chad

[Mark Markow]

what you might look at. is how sharp the teeth are on the cam if you wore out the bronze gear i bet they are pretty sharp . i always make it a pratice when installing a roller or billet core type cam to debure the gear on the cam . and you could even go as far a polishing the sides of the tooth . a slighly worn fine scotch bright wheel works well. and to prolong the life of the bronze gear you could drill a tiny hole in the base of he distributor, take the gear of and drill up at an angle into the band that seals off the oil gally for the lifters .so that it will spay oil on gear. a savvy engine builder told this trick to me to help my street car live with a roller cam.
good luck

[treessavoy]

Had a friend that this happened to in his Mopar, it turned out that the cam bearing weren't aligned and the cam pretty much seized up on the first run and broke the pin and ate some of the dist.gear.

Just a thought

JimR

[magnumv8]

One other thing to consider....if the block and or heads are milled and the difference isn't made up with head gasket thickness this lowers the intake enough to throw off the gear alignment between the cam and distributor gears.....a bronze gear will wear into a pattern with the cam gear and the composite one will not......what would need to be done is to shim the distributor to get the correct gear wear pattern.....just something else to consider......


D L Rambo......

[greg fulk]

what brand cam are you running?

[Mike Taylor 3601]

I would guess that since you had wear problems before, you need to check how cam/dist gear are meshing and check teeth on cam first. If cam gear teeth are sharp from wear you'll have to replace cam because it will eat every dist. gear you put on it.
Most likely you're gears are too tight or loose ( backlash) or gear on cam is worn and eating dist. gears.
Mike Taylor 3601

[Chad E532]

Thanks for all the good feedback.
The cam is a Lunati solid roller. I will definitely have a look at how sharp the teeth are when I get the engine out of the car and torn down. I am envisioning pulling the cam out and having the dist teeth lodged into the cam gear. The bronze gear I had in before was in for 2 full seasons so it did have a number of runs on it and I did not measure how much it was worn but it was more of a visual wear pattern that was a few thousands deep so it was not all torn up or anything like that. The intake and heads have not been machined and I run a stock thickness gasket. The block has been decked about 0.020" so that would drop the intake down.
I guess I have never checked the dist to cam gear alignment / clearances before. Anyone have any tips on how to check this out?
Thanks,
Chad

[magnumv8]

Start by checking your camshaft endplay before you remove your existing cam....just use gear marking compound ( same as rearend gear setup) get your cam (existing or new) and set it up with the proper endplay in the block put compound on the distributor gear, drop it in, lock it down....with either an extra hand or a long reach put a slight drag on the distributor shaft and rotate the cam a few revolutions ( in the proper direction)....pull the dist. and check the pattern, adjust if needed.....


D L Rambo.....

[Mike Taylor 3601]

You can also look at it with crank out set heads intake on with few bolts and gaskets install dist. without rotate assm. you can see gears pretty easy make sure timing gear is on so cam will be in right location.
Mike Taylor 3601