Are our distributor gears "melonised"?
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Are our distributor gears "melonised"?
Or hardened? -I don't even know what "melonised" means-
I have a Comp cams XR294HR-10 hyd roller cam. (242*/248* 110LSA :D )
and the stock distributor gear. After approx 100 miles(new motor and gear) there is very pronounced wear on the dist gear. I did the groove in the lower band of the dist body for additional oil on the gear too. Also loaded the teeth with moly assembly lube for the initial firing of the motor.
I called Comp and while their cust service wasn't that great, they said they design these cams to run with the stock dist. I should mention there is a HV oil pump too.
I then tried yet another gear and drove for approx 10 miles around town. Pulled dist and again, pronounced wear.
I'm no expert, but it seems like excessive wear.
I was told not to use a bronze gear as it would wear even quicker. That they are for race motors where they can sacrifice the dist gear instead of the cam.
Also that I should be using a melonised gear. Or hardened. What is melonised?
The engine builder wants to see the dist gear so he can see what's going on. Additionally he says he will warantee out me another cam no prob, but I would still like to know why this is happening.
What's your experience?
I have a Comp cams XR294HR-10 hyd roller cam. (242*/248* 110LSA :D )
and the stock distributor gear. After approx 100 miles(new motor and gear) there is very pronounced wear on the dist gear. I did the groove in the lower band of the dist body for additional oil on the gear too. Also loaded the teeth with moly assembly lube for the initial firing of the motor.
I called Comp and while their cust service wasn't that great, they said they design these cams to run with the stock dist. I should mention there is a HV oil pump too.
I then tried yet another gear and drove for approx 10 miles around town. Pulled dist and again, pronounced wear.
I'm no expert, but it seems like excessive wear.
I was told not to use a bronze gear as it would wear even quicker. That they are for race motors where they can sacrifice the dist gear instead of the cam.
Also that I should be using a melonised gear. Or hardened. What is melonised?
The engine builder wants to see the dist gear so he can see what's going on. Additionally he says he will warantee out me another cam no prob, but I would still like to know why this is happening.
What's your experience?
Safety Car
Joined: Dec 2000
Posts: 3,767
Likes: 5
From: Jacksonville Fl
Re: Are our distributor gears "melonised"? (89 Paul in Cal)
The factory roller cam has a cast iron distributor gear pressed onto it's end, thereby negating the need for any exotic distributor shaft gear.
Aftermarket roller cams usually do not have a pressed on gear.
The Roller cams I always use, Schneider, are all one piece forged steel, and I use bronze gears on them. They typically last about 10-20K miles.
I have never used a melonized gear.
[Modified by BBA, 7:28 PM 6/27/2003]
Aftermarket roller cams usually do not have a pressed on gear.
The Roller cams I always use, Schneider, are all one piece forged steel, and I use bronze gears on them. They typically last about 10-20K miles.
I have never used a melonized gear.
[Modified by BBA, 7:28 PM 6/27/2003]
Team Owner
Joined: Mar 2001
Posts: 54,124
Likes: 30
From: Cincinnati, Oh USA
Re: Are our distributor gears "melonised"? (89 Paul in Cal)
From http://www.chevyhighperformance.com
One of the consequences of the change to a hydraulic-roller camshaft in GEN VI big-blocks is the need for a compatible distributor gear. The gears installed on early-model distributors will wear abnormally when used with the steel camshaft in a GEN VI engine. GM Performance Parts offers an HEI distributor for H.O. engines as PN 1104067. This distributor has a specially treated (melonized) gear that is compatible with a steel hydraulic-roller camshaft. This gear is also available separately as PN 10456413 for installation on early-model distributors.
The distributor gear is subject to high loads because it also drives the oil pump. If the melonized gear noted above is used with a high-volume oil pump, it may be subject to rapid and excessive wear. One remedy is using a 6016 steel distributor gear (PN 10457708) from a ’96-or-newer L29 distributor. The L29 distributor gear must be modified by enlarging its shaft hole from 0.470 to 0.500 inch to fit the shaft in an HEI or early-model points-type distributor.
One of the consequences of the change to a hydraulic-roller camshaft in GEN VI big-blocks is the need for a compatible distributor gear. The gears installed on early-model distributors will wear abnormally when used with the steel camshaft in a GEN VI engine. GM Performance Parts offers an HEI distributor for H.O. engines as PN 1104067. This distributor has a specially treated (melonized) gear that is compatible with a steel hydraulic-roller camshaft. This gear is also available separately as PN 10456413 for installation on early-model distributors.
The distributor gear is subject to high loads because it also drives the oil pump. If the melonized gear noted above is used with a high-volume oil pump, it may be subject to rapid and excessive wear. One remedy is using a 6016 steel distributor gear (PN 10457708) from a ’96-or-newer L29 distributor. The L29 distributor gear must be modified by enlarging its shaft hole from 0.470 to 0.500 inch to fit the shaft in an HEI or early-model points-type distributor.
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Re: Are our distributor gears "melonised"? (jfb)
Thanx so much gentlemen,
in my case, I am using the small dist with the external/remote mount coil. I dunno why, but it has a smaller shaft around .420 approx. Hard to find gears for this one.
well, I am gonna try and drive this thing 600 miles round trip and see if it survives. I will have the back up dist w/ gear with me.
in my case, I am using the small dist with the external/remote mount coil. I dunno why, but it has a smaller shaft around .420 approx. Hard to find gears for this one.
well, I am gonna try and drive this thing 600 miles round trip and see if it survives. I will have the back up dist w/ gear with me.
Drifting
Joined: Nov 1999
Posts: 1,801
Likes: 2
From: St. Paul MN
Re: Are our distributor gears "melonised"? (89 Paul in Cal)
This is what my melonized gear looked like after about 5000 miles. I was using the m55hv oil pump and hadn't grooved the dist. shaft to allow oil to drip on the gear. I have since switched to a m55a pump and grooved the dist shaft. I havn't driven the car very much yet to pull the dist. and take a look for wear. I'm just crossing my fingers for awhile. I had a hard time getting anybody to give me any info from GM regarding this. Good luck with yours.
Thread Starter
Le Mans Master
Joined: Jul 2001
Posts: 8,183
Likes: 3
From: Santa Maria, CA
Re: Are our distributor gears "melonised"? (Bob86ZZ4)
wow Bob! Thank you so much for this info and pic!!!!
Dare I ask how the cam gear did? I was told the teeth particles actually bond into the main bearings if severe enough. I think I will switch to a regular volume pump also. Is it just a spring change or the whole unit?
Did the car still run ok with that amount of wear? How did it act just before it failed?
Thanx again, amazing pic.
[Modified by 89 Paul in Cal, 11:46 PM 6/27/2003]
Dare I ask how the cam gear did? I was told the teeth particles actually bond into the main bearings if severe enough. I think I will switch to a regular volume pump also. Is it just a spring change or the whole unit?
Did the car still run ok with that amount of wear? How did it act just before it failed?
Thanx again, amazing pic.
[Modified by 89 Paul in Cal, 11:46 PM 6/27/2003]
Drifting
Joined: Mar 2001
Posts: 1,636
Likes: 3
From: Lafayette IN
Re: Are our distributor gears "melonised"? (89 Paul in Cal)
I think I will switch to a regular volume pump also. Is it just a spring change or the whole unit?
You will need a new oil pump if you want to go with standard volume.
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Re: Are our distributor gears "melonised"? (HighHopes85)
Le Mans Master
Joined: Jul 2001
Posts: 9,622
Likes: 16
From: absecon nj
Re: Are our distributor gears "melonised"? (BBA)
ok so what if your using a zz4 roller cam with an small dist. from a 87 fbody that didnt have a roller cam in it ,do we still need a hardened gear or will the stock one work,.
