gkull

Years ago I ordered a custom billet steel solid roller from their list of lobes PDF for my 427 SBC. It was to have a sleaved on distributer gear for using common steel dizzy gear that comes with digital MSD E curve pro billet distributers. Two weeks delivery supposedly, but after 30 days and repeated phone calls I recieved a billet cam with out the sleeved on dizzy gear. They said NO problem and I could call up summit racing and get their super Polymer dizzy gear compatable with billet cams at cost.

Yesterday was a cool 50 degrees and I decided to take the vette over to my hot rod buddies house and the motor just couldn't get much heat in it maybe 150 degrees in 20 some miles. I should have disabled one of my spall fans that constantly run. So anyway on the way home I WOT ran it through the 2-3-4th gear when the motor went silent. I whipped it into "N" and coasted into a shopping area about 3/4 miles away. tried to start it while coasting and nothing in the way of spark. So in the parking lot I'm checking all the wiring and I hit the starter with the cap removed and saw NO rotation. So I called my buddy and he took me to my house to get a spare dizzy gear, some tools and a timing light. Just watched the #1 cylinder valve events with the valve cover off. Then cranked the damper to 20 degrees advance and installed the dizzy with the rotor right on #1 wire. The old vette fired up and the cap needed a minor move to get my 20 degree initial with the vacuum advance off. Then I drove home. My oil pressure gets up to 70 over 4500 rpm which you would think wouldn't be a problem except with a bad product.


Sheared off teeth!

DWAVette

So that gear is plastic!!??

REELAV8R

Polymere gear in a shear application. Not too surprising.
It's ok in compression, if supported, I wouldn't use it in a shear application.

Rescue Rogers

Im not tryi8ng to sound like a know-it-all, AND I do rub people the wrong way because I am a know it all and a general pain in the *** and have been called a bully,but....why would you buy a plastic drive gear...seams like a bad chioice...we bitch about the plastic timing gears chevy used to use...bad idea, they stopped doing it. Muncie went to plastic drive gear on their 4 speed, we bitched about it being a bad choice....and you chose a plastic gear because Comp says its universal ? And you have a performance motor and drive it like its rented and expect plastic to last.......You should have used melonized. Sorry but I wouldnt blame Comp for this choice...Distributor Gear Materials:

1. Cast Iron
2. Composite (offers great life, conforms well to the mating cam gear, and is compatible with ANY camshaft gear material)
3. Melonized or hardened steel (material that OEMs use with factory roller cams; many aftermarket distributor manufacturers use these as the default gears for their distributors)
4. Bronze (conforms well to the mating camshaft gear and will not damage the camshaft gear, but it is a self sacrificing gear intended to be used in race applications only and should be replaced about once a year)

If you have a cast iron hydraulic or solid flat tappet cam, your distributor gear options are:

1. Cast iron distributor gear
2. Composite distributor gear

If you have an austempered ductile iron hydraulic or solid roller cam, your two options are:

1. Melonized or hardened steel distributor gear
2. Composite distributor gear

COMP

Cams recommends the composite gear because it is compatible with all camshaft gears – flat tappet, austempered cast iron cores, and billet cores. If the steel gear is not hardened, it is not compatible with either of the roller cam types.

Note: If you have an austempered core hydraulic roller cam and a .500? shaft distributor with a steel gear, verify with the manufacturer of the distributor that the steel gear they use is a melonized or hardened steel material and it will work fine.

–Tech Tip courtesy of Comp Cams
The last two sentences are what you are referring too I think. The last sentence should have steered you towards a melonixed gear

augiedoggy

I dont know if you missed it but he had the composite gear because thats was comps solution to remedy the mistake they made on his order of the cam with the missing sleaved on distributor gear... Id feel they were at fault here too at least partially

My question is how many years (and miles) did it run for before failing? Just curious..

speedreed8

The whole root of the problem is that you cheaped out 👍

Gale Banks 80'

Are You using a Tach Drive Distributor ?

Rescue Rogers

No i had read that was their suggestion. But he still went and bought it from summit that has a pile of different parts....its plastic. Never buy a plastic internal engine part or a plastic internal gun part. They will eventually fail and its going to be when you need it. MIM is the same process but in a **** metal form. Dont buy injection molded parts either. Its just a shittier version of cast parts.

I got rid of my mechanical tach drive because the suppliers went to cheap chinese plastic drives on the cables....they just kept breaking

Jebbysan

The composite gear is not cheap......it works for some and others have had the same results Gkull has......they were introduced in 2007 and I used about a half dozen of them until they started to come apart.....never used another after 2008......
Full race stuff gets bronze......street gets melonized on a billet core.......most all of my street stuff gets a standard iron gear......
Interestingly.....Ford's SB roller cams require a Melonized or hardened gear.....have forever......said right in the Motorsports catalog 20 years ago to use this if you buy this.....so this is not a new or ever newer-ish thing.

Jebby

walleyfisher

I have had a full solid roller high lift Comp Cam with Rhoads solid roller lifters set up in my motor since 2001, I would go thru a bronze distributer gear every 2 summers, (teeth would get thin and sloppy) since I switched to the plastic version (composite) I now on my 3rd summer and it still looks new

bonesbrakr

I agree this is a problem with Comp. They sent you the wrong cam as spec'ed. I know you wanted to get the car back together and driving but you should of demanded a new camshaft as per specs or your money back.

gkull

That Composit gear is $143 now. It was the end of winter and the up coming SCCA road racing season. My block was done and I had to get it together for the points races. The 30 day delay was getting down to crunch time and to send it back would feasably add another 30 days which I couldn't do. I wasn't going to run bronze and comp cams said at cost so I bought 3. Good thing because they seem to last about 4 to 5 years being swapped in and out of motors. My new 434 probably needs thinner oil because it's so cool now.

It was just forgetful on the cam grinders part who didn't read the full order about the billet steel cam with a sleaved on gear. They wanted to recieve that wrong cam back before they would make and send me another. The two broken gears have been 4-5 years apart

Billet steel 252/256 @ .050 .685 inch intake .714 exhaust with Dart 227cc full race ported 2.10 intake valves 1.625 exhaust. Composit gear and Crane cams utra pro solid roller lifters

https://www.summitracing.com/parts/c...RoCh2oQAvD_BwE

wwiiavfan

Did the oil pump screen catch all the shrapnel from that dizzy gear on your drive home?

gkull

I'm just going to change the oil and filter