melonized gear, which is which?

[mickeykreg]

I've got two .490 HEI distributor gears that I thought I had tagged. I know one is melonized and one is not. Guess, now I don't know for sure which is which. Is there a way to tell the difference?

[Ziegelsteinfaust]

Melonized is for roller cams.

Cast iron is for flat tappet cams.

Bronze is for I think Billet cams.

Composite is universal. But I would trust it myself.

I think there is one more I forgot.

Distributor gears as you know have to match the cam style you have, and while I have a melonized gear in my 69 Camaro with the LT1 reverse cooled engine. It was what was already there to drive the oil pump from the cam. So I got a new gear to fit my small cap distributor.

Supposedly even a melonized may not work on a roller cam if it had a different style to begin with. I have no real experience, but I did run across it on the internet. So it is likely false.

[mickeykreg]

Sorry, I wasn't very clear in OP. I've got a cast iron gear and a melonized gear and I can't tell them apart. I know the melonized is harder than cast iron, but I don't know how to figure that out either.

[Ziegelsteinfaust]

Is there a part number stamped into them?

A cast iron should have a thunk kind of sound where hardened gear should be more like a bell.

You could try to dimple them with a punch. The softer cast iron should dimple easiest. Where the hardened melonized should barely dimple.

[mickeykreg]

No part number. Hitting them with a punch sounds like a good idea. Thanks for the help

[garyd1961]

The melonized gear should have a texture to the finish the regular cast gear is smooth.

[Ziegelsteinfaust]

Originally Posted by mickeykreg

No part number. Hitting them with a punch sounds like a good idea. Thanks for the help

Your not supposed to lay in to it. Just a simple tap would give the answer

[Ziegelsteinfaust]

Originally Posted by garyd1961

The melonized gear should have a texture to the finish the regular cast gear is smooth.

My melonized gear was almost visually identical to my cast iron gear. Slightly darker color, but they can also be slightly lighter or grayer.

[garyd1961]

Originally Posted by Ziegelsteinfaust

My melonized gear was almost visually identical to my cast iron gear. Slightly darker color, but they can also be slightly lighter or grayer.

They make a melonite coated gear that looks like the standard gear but it's not for a roller cam. All the melonized gears I've seen have a texture to the outside.
Also I believe the gear for the flat tappet cam is actually steel not cast iron.
I have to say that I have never seen a factory melonized gear so I'm not sure what they look like but all the after market gears from Summit or Jegs have a texture appearance like a cast iron pipe fitting.
The gear for a cast iron flat tapped cam is steel that's why you can't run it on a steel roller cam. They will wear each other out. They also make a steel roller cam with a cast iron gear sleeved on and you can run a steel distributor gear on them.
Either way make sure you have the right gear.

[mickeykreg]

Ok, thanks for the help. So melonized on the right then, correct?

[garyd1961]

Originally Posted by mickeykreg

Ok, thanks for the help. So melonized on the right then, correct?

Yep, the one on the right looks like all the melonized gears I've seen.
Make sure it's the right shaft size. The MSD shaft is larger than the factory shaft.