So, looks like I had a distributor gear go bad. Never had one go bad before, ever, until now. Looks like the root cause of the failure was the aftermarket company Summit uses to make these things put a large bevel in the top of the gear tooth flank where it shouldnt be. The net result is obvious when 40% of the tooth face is missing: overloading and surface fatigue failure (see pic). These companies never seem to run out of creative ways to make life difficult.

I put the correct A/C Delco gear in there without the damn bevel and, not surprisingly, the cam gear was kind enough to restore the bevel (see other pic) on its own accord since it still has the old wear pattern impressed in it. Aside from the really funky wear pattern, the cam gear looks ok.

So, I could pull the engine, strip it back down, replace the cam with a fresh one and the right gear... Or, be lazy, grind the bevel into the new gear, and leave it for a while until I feel motivated enough to do the former. Question is, will it last for a while until I get around to putting a new cam in it? I havent gotten around to buying a new car yet, so I still need the camaro for a while longer to get to work.

 

If the bevel is problematic, try stacking gaskets between the intake manifold and the dizzy. ( You are using at least one gasket there already, right? ) You can easily raise the dizzy a sixteenth of an inch with no worries at all. Beyond that, you have to be sure it still engages enough of the oil pump drive shaft. My Accel Blueprint 59107c came with a bevelled gear, which has been no issue in several different 350s now, including HF and GM HR cams.

 

The problem is the odd wear pattern the old gear left in the cam. From the new one that just got trashed after a 100 miles or so, it looks like the teeth on the cam have a deep concave groove where the old worn gear was riding, so its totally fubar at this point.

Can a bronze gear be used with the ductile iron roller cams? Seems 10 extra minutes to change a bronze gear during a tune-up is a helluva lot easier than changing the cam.

 

Curious if you maybe started with a steel gear on the dizzy, instead of iron? I was protesting any problem with the factory shape of the gear, and wondering if you had a Chinese intake manifold, while you were on the cam wear. Oops, guess I was tired, sorry. Anyway, you can try the bronze gear on the dizzy with any cam, but once the cam gear is hurt, it'll likewise hurt a bronze gear way faster than another iron gear. If you go to a steel gear on the dizzy, that may well finish off the cam, and a nylon gear costs nearly as much as just trying a new HF cam. I have no experience with those new nylon gears, and they're much cheaper than a new custom roller cam. If you go that route, I'd like a follow-up about your results.

 

I was just thinking the same thing about the original gear. The GM one is soft steel with a Melonite coating (oe roller). I used a diamond bit to put the bevel back in to try it. Like cutting through butter.

The Summit one is forged steel or something. Its hard as HELL. The diamond tip just scratches it, and thats about it. This is like a gear for a transmission. All distributor gears should be softer than the cam AFAIK, not harder... The cam gear obviously wore a lot more than the distributor gear. Ill be using a GM one next go around.

The manifold is an Edel victor-e, and it doesnt seem to have any alignment issues, but the wear pattern is a little low on the gear, so it could sit a tad lower.

Im a little leery of the composite gears. Wear is very good on those as theyre plastic. But they seem to sheer all the teeth on high RPM clutch dumps and other shock loads. No telling how it would work in the dead of winter, either.

 

Steel gears seem fine with steel core cams, like Comp HR but not older Crane HR, so long as the mesh is good and there's enough oil getting in there. Before HR, it was all iron gears with iron-core cams. Since then, melonited gears were standard for steel-core, iron gears for Crane HR, and your thinking about the dizzy gear being softer became wide-spread, even for front-dizzy engines like the Ford Windsor. Those new nylon gears are supposed to last far longer than the bronze, but otherwise work with any cam core. I'm so big on changing cams that I never wear out any gear in any combo. The perfect cam isn't possible, and if you don't swap it, you don't learn as much.

 

The composite gear will definitely have very good wear charicteristics since its so dissimilar from the cam gear. But, will it last through something like a clutch dump or a cold winter start? First gen Navstar/PSD 6.0L diesels had composite HP oil pump gears, and those didnt fare so well. Another one of those things that works great in the lab, but fails out in reality.

I guess just using something like a standard iron GM gear may be a good compromise since I like to drive the car a lot.