Here is my understanding:

1. GM Factory roller engines use a melonized distributor gear.

2. GM factory flat tappet engines used iron gears.

3. Aftermarket steel billet roller cams require a bronze gear.

4. Some aftermarket roller cams have a pressed on gear that allows the use of a melonized gear.

Questions:

1. Are assumptions 1-4 above correct?

2. Is it correct that a melonized gear cannot be substitued for a bronze gear on steel billet cams?

3. Do all aftermarket hydraulic roller cams accept melonized distributor gears now? I got a custom ground comp hydroller a few years ago and it accepts melonized. Looking through comps catalog it looks like all their street hydrollers do. But how about Crane or Lunati? I'm considering getting one of Harolds Voodoo deals when he releases the hydrollers, but I want a melonized gear. Not interested in the hassle of a bronze gear.

Thanks!
Markus

Marcus,
I do not think you can make any assumptions. There are too many differences between the manufacturers. Use whatever the manufacturer says to use for the particular cam you purchase. In my opinion, it's cheap insurance to replace the distributor gear every time the cam is changed.

Originally posted by zwede:
Here is my understanding:

1. GM Factory roller engines use a melonized distributor gear.

2. GM factory flat tappet engines used iron gears.

3. Aftermarket steel billet roller cams require a bronze gear.

4. Some aftermarket roller cams have a pressed on gear that allows the use of a melonized gear.

Questions:

1. Are assumptions 1-4 above correct?

2. Is it correct that a melonized gear cannot be substitued for a bronze gear on steel billet cams?

3. Do all aftermarket hydraulic roller cams accept melonized distributor gears now? I got a custom ground comp hydroller a few years ago and it accepts melonized. Looking through comps catalog it looks like all their street hydrollers do. But how about Crane or Lunati? I'm considering getting one of Harolds Voodoo deals when he releases the hydrollers, but I want a melonized gear. Not interested in the hassle of a bronze gear.

Thanks!
Markus =
To your original questions:

1 All GM cams & any cast cam can use the GM melonized gear regardless of whether it is a roller or flat tappet.
The only iron gear I know for a fact that has a problem with cast hyd roller cams is the MSD.
Their fix is to use their "marine" gear which I am reasonably sure is the GM Melonized gear honed to fit.
Not real sure how the engine knows it is in a boat but apparently it does :D
My fix is to just buy the GM gear & hone it then I know what it is.

2 see above.

3 A billet cam needs either a bronze gear or the new composite Comp gear which is showing promise according to Comp.

4 Any cam manufacturer can grind a billet with the cast gear option, all they need to do is get the right core ;)

Just for info, Melonizing is a surface treatment not a special material.
Here is some info:
Melonite (http://www.trutecind.com/heat/melon.htm)

Thanks, Mike. Very informative. So I guess the only question left unanswered is if the voodoo hydraulic rollers will use a cast gear or not. Harold???

Markus

FWIW, I just have my cams done on a blank from Crane that has the pressed on iron gear. I just use stock regular old dist gears with no issues. Seems to solve all the hassles for $50...less than the price of a trick gear.

JIM

PS- C'mon...let get those heads to Trevor for some flowbench port work!

Don't get it torn down....we're going to track soon when Nick gets his together. Donny is ready too!

FYI Mike (and others), I've had a few friends now destroy a couple of of the Comp composite distributor gears. They were originally developed as a NASCAR piece; guess what, NASCAR motors run dry sump and the gear only has to spin the distributor. It seems the composite gears work great as long as they don't have to drive an oil pump, so they're out for 99.9999% of all street applications. Your mileage may vary however.

I wouldn't run an MSD Melonized gear on ANY cam even if somebody paid me; I've had one destroy itself and the cam gear, and one nearly shred itself. Both were on Comp HR's. I am now a GM Melonized gear person all the way, thanks to Mike's tip. So far, so good. graemlins/thumbsup.gif

Troy

I've heard both good and bad concerning the Comp carbon polymer gear used with wet sump pans in endurance racing. Some barely last one race, others have been trouble free with little or no wear after a few races.
Comps tech people say these gears are fine for running on the street as long as end play is kept to an absolute minimum.

Iv'e got one, and shimmed it to Comps spec, on my yet to be fired 509. We'll see just how long it lasts when the motor is installed.

John

John: When you say "end play", are you talking about the distributor shaft play or camshaft play or both?

/Markus

Mike,
I tried to get Lunati to put the cast gear on my cam, and they more or less politely refused. Lunati also seems to be having a little trouble making the cam specs they have printed on their webpage and what they quote when you call match up with what they actually send you. I think Lunati has a great opportunity with all of Harold's R&D on the upcoming Voodoo line. I hope they make some level of effort at improving the customer service training and product knowledge of the people who will actually be selling these new cams.

Markus,

It's distributor shaft end play. The end play specs that Comp gave me were tighter than what is recommended by MSD. When I querried MSD by e-mail, they felt Comp's spec was too tight. When I e-mailed Comp back about MSD's reply, they were emphatic about maintaining their minimum recommended end play. So I orderd a MSD shim set and set it to Comps spec.

I also grooved the distributor housing (grumpyvette @ Chevy Talk)to increase oil lubrication to the cam/distributor gear. Will see what happens once it's fired. Looks like I'll be checking it frequently at first to make sure I don't end up with a more serious problem.

A further note, Comp felt there shouldn't be a problem using this gear with a HV pump, which I have.

John