HEI distributor gear help needed.

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Mar 13, 2005 | 10:31 AM

KENS80V

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Melting Slicks

Joined: Aug 2004

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From: Oakbank Manitoba

HEI distributor gear help needed.

I'm retrofitting a 1990 Corvette induction system into my 1980 Corvette. I'm confused about the 1990 Vette distributor gear....I thought it was supposed to be bronze to go with the factory hydraulic roller cam. I was about to remove it to rebuild the distributor and discovered it was iron. The cam that is in my car is not a hydraulic roller and only requires an iron gear. Can anyone enlighten me on this subject?

Thanks
Ken

Mar 13, 2005 | 11:14 AM

tjwong

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From: Portland Oregon

Quote:

Originally Posted by KENS80V

GM did not use any bronze gears in any stock engine that I know of. Since they went to roller cams, GM has been using what they refer to as a "melonized" gear. This is a process that the gear goes through for additional hardening and coating to be more compatible with the induction hardened steel cores that GM used for their cams. These gears are OK to use with cast gears that are used by Crane and Comp. Cranes billet roller cam cores do have a cast gear pressed onto their cores, Erson uses the same Crane cores with their roller grinds, Comp of course uses their "ostempered" cores which also do not need a bronze gear. Crane also offers steel distributor gears that are compatible for use with steel billet cores that do not use a cast gear. But in the case of LT1 which uses a smaller diameter drive gear, there is no aftermarket replacement for them.

Mar 13, 2005 | 06:33 PM

KENS80V

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Melting Slicks

Joined: Aug 2004

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From: Oakbank Manitoba

So a melonized gear is backwards compatible with an older non hydraulic roller cam but an original 1980 HEI distributors gear is not forwards compatible with a newer style hydraulic roller cam! Is this correct thinking?

Thanks
Ken

Mar 13, 2005 | 06:51 PM

JAKE

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From: Kempner Texas

Quote:

Originally Posted by KENS80V

That seems about right, based on my personal experience. I've been through three gears, to stockers (non-melonized) and a bronze.

Even though was told the stock non roller gear would work, it won't, at least not for very long.

One wore so badly that the engine actually shut off on me enroute to the grocery store.

The bronze gear only lasted a couple thousand miles, so that wasn't the answer.

The melonized gear seems to be lasting, although I haven't had it out to actually check it. I'm doing like HAL recommended in "2001: A Space Odyssey"; I'm running a "Failure Mode Analysis" on the gear. LOL

Jake

Mar 13, 2005 | 09:52 PM

tjwong

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From: Portland Oregon

Quote:

Originally Posted by KENS80V

The part number for the GM melonized gear is: 10456413

It will fit all GM distributors. If you have a MSD or other aftermarket distributor with a .500 diameter shaft you can order a MSD gear which are also melonized. Comp Cams also is marketing a gear made from some kind of high strength polymer material. Their claim is that they would outlast a standard iron gear and are compatible with any cam gear. But at a cost of over $125 it should be compatible

They have this gear available for GM and non-GM distributors.

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