Distributor Gear Material ? - Team Camaro Tech
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post #1 of 5 (permalink) Old Mar 14th, 19, 09:49 AM Thread Starter
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Mike
 
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Distributor Gear Material ?

It appears that several of the aftermarket distributors are stating that they have a 4340 steel... or a chrome moly steel distributor gear.
I've always read that you should use a melonized steel distributor gear (or a composite gear) when installing a ductile iron or billet steel roller cam.

Does anyone know if the 4340 steel, or the chrome moly steel distributor gear is similar to the melonized steel distributor gear?... and can they safely be used with a ductile iron or billet steel roller cam?
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post #2 of 5 (permalink) Old Mar 14th, 19, 10:19 AM
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Re: Distributor Gear Material ?

IMHO, stay with melonized gear on the cam. Cam companies can put melonized gear on a billet cam core
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post #3 of 5 (permalink) Old Mar 14th, 19, 12:10 PM
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Re: Distributor Gear Material ?

Quote:
The process is called Melonite and is a proprietary process. It is a salt bath Ferritic Nitrocarburize procedure which uses a cyanide base. The process is accomplished at temperature around 1050F. It is usually (but not in all cases) applied to low alloy steels to form a surface generally of iron nitrides.
That said it is ONLY required with a billet steel cam core. One has to be harder than the other (and iron nitride is as hard as the hinges to he!!) for both to live. Unless you ordered a billet steel cored cam you don't have one.

Racers use brass with their custom ground billet steel cores because as expensive as a brass gear is it is by far cheaper than replacing a cam. And you will be replacing it regularly in competition due to the wear caused by a big oil pump running high volumes at a high pressure (I have three on a nail just inside the tool room door as they wear out quickly).

With a street driven car and a cast iron core cam (ductile iron or grey iron is still cast iron, not steel) the factory supplied steel distributor gear works well for a 100,000 miles or more.

Big Dave
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post #4 of 5 (permalink) Old Mar 21st, 19, 07:14 PM Thread Starter
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Mike
 
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Re: Distributor Gear Material ?

Quote:
Originally Posted by Larger Dave View Post
That said it is ONLY required with a billet steel cam core. One has to be harder than the other (and iron nitride is as hard as the hinges to he!!) for both to live. Unless you ordered a billet steel cored cam you don't have one.

With a street driven car and a cast iron core cam (ductile iron or grey iron is still cast iron, not steel) the factory supplied steel distributor gear works well for a 100,000 miles or more.
Dave, Thank you for the explanation. The cam I currently have installed is a Comp Cam Hyd Roller made of austempered ductile iron.
Based on the information I read on the Comp Cams website (see below), it states that I should be using a melonized steel distributor gear with my cam.
"Cast iron and composite gears are suited for hydraulic and solid flat tappet cams, while melonized steel and composite gears mesh with austempered ductile iron hydraulic and solid roller cams, or those camshafts that have been nitrided. Finally, either bronze or composite distributor gears are your options if your camshaft is a billet steel hydraulic or solid roller."

I currently have an HEI with a melonized steel gear, but I am in the process of converting an MSD 8360 "Ready to Run" distributor (that died on me several years ago) to a remote mounted GM 4-pin HEI module. The MSD distributor currently has a ductile iron distributor gear.
Should I be changing the MSD distributor ductile iron gear to a melonized steel gear to work with my roller cam?

Unfortunately, I can not take the melonized steel gear from the HEI and install it on the MSD distributor due to the different shaft sizes (HEI .491" Dia vs MSD .500" Dia).
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post #5 of 5 (permalink) Old Mar 21st, 19, 09:51 PM
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Dave
 
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Re: Distributor Gear Material ?

A hardened (melonized gear) works on all cams. Ductile iron is still cast iron differing only in the heat treatment process to control the rate of growth of the iron crystals. Steel is an alloy or iron with carbon and is harder than cast iron (which is why you use tool steel to machine cast iron). This allows the cam to wear leaving the distributor gear untouched.

If you had an expensive billet steel cam core you would use a composite plastic or yellow brass gear to ride on the cam because distributor gears are cheaper to replace than a custom ground cam. How fast the gear wears is determined by the load. So thick oil and a high pressure high volume pump will wear out your distributor gear faster than a standard OEM Melling replacement oil pump.

Big Dave
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