502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR?
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Safety Car
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From: VASS, NC, USA
502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR?
IVE GOT THE GM 502/502. INSTRUCTIONS STATE WHATEVER DISTRIBUTOR IS USED MUST HAVE A MELONIZED GEAR. I HAVE AN AFTERMARKET POINTS TYPE TACH DRIVE DISTRTBUTOR THAT FITS AND FUNCTIONS FINE IN MY 427, BUT IM WORRIED ABOUT THE GEAR
WHAT IN THE WORLD IS MELONIZED, AND HOW CAN I TELL IF IT IS OR NOT
WHAT IN THE WORLD IS MELONIZED, AND HOW CAN I TELL IF IT IS OR NOT
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Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (MELVIN)
Melvin,
I'm not sure, but I think the 502 has a roller cam and might need a special distributor gear to go with the roller cam. I don't know enough about "Modern" engines to tell you for sure, but I think they require a bronze gear. Or maybe it's a steel gear, hell I don't know. Maybe one of the real experts will see this and answer.
I'm not sure, but I think the 502 has a roller cam and might need a special distributor gear to go with the roller cam. I don't know enough about "Modern" engines to tell you for sure, but I think they require a bronze gear. Or maybe it's a steel gear, hell I don't know. Maybe one of the real experts will see this and answer.
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St. Jude Donor '03
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (MELVIN)
Did you buy the complete engine kit? If so, it came with an HEI distributor that has a melonized gear on it. You should be able to swap it out to your old distributor. I'm sure it has to do with the hardness of the gear and use with the roller cam. You can also find out from the manufacturer of you existing distributor about the gear that is on it. I know that MSD distributors already have melonized gears on them.
Good luck
Dave
Good luck
Dave
Drifting
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From: Fremont, CA, USA
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (MELVIN)
MELVIN-----
The 502/502 engine uses an hydraulic roller cam manufactured from a steel core. For compatibility, a melonized distributor drive gear MUST be used. This part is available from GM if you don't already have one. There is no way that I know of to discern the difference between a melonized and non-melonized gear. So, if you have any doubts or can't absolutely confirm that the one you have is melonized, I'd play it safe and obtain a known melonized gear. The melonized gear that you need if you don't have one is GM #10456413 and currently GM lists for $35.19.
If your engine came with a distributor from GM, that distributor will have the melonized gear installed.
Do not get any ideas about using a brass gear. A brass gear will work, but they have a very short life. I NEVER recommend the use of one in a street engine. They were originally intended for aftermarket mechanical lifter type roller cams which were among the first cams to use steel cores. However, most of these cams are intended for and used for racing applications. For these applications, brass gear wear is not an issue. For street use, it is a BIG issue. So, don't make the mistake of letting some "speed shop counterman" talk you into a brass gear.
The 502/502 engine uses an hydraulic roller cam manufactured from a steel core. For compatibility, a melonized distributor drive gear MUST be used. This part is available from GM if you don't already have one. There is no way that I know of to discern the difference between a melonized and non-melonized gear. So, if you have any doubts or can't absolutely confirm that the one you have is melonized, I'd play it safe and obtain a known melonized gear. The melonized gear that you need if you don't have one is GM #10456413 and currently GM lists for $35.19.
If your engine came with a distributor from GM, that distributor will have the melonized gear installed.
Do not get any ideas about using a brass gear. A brass gear will work, but they have a very short life. I NEVER recommend the use of one in a street engine. They were originally intended for aftermarket mechanical lifter type roller cams which were among the first cams to use steel cores. However, most of these cams are intended for and used for racing applications. For these applications, brass gear wear is not an issue. For street use, it is a BIG issue. So, don't make the mistake of letting some "speed shop counterman" talk you into a brass gear.
Team Owner
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From: Virginia USA
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (Rolling Thunder)
I know that MSD distributors already have melonized gears on them.
Are you 100% sure all MSD distributors come with melonized gears? I was just wondering because I have a ZZ4 with a MSD 8572 tach drive distributor install and just want to make sure I don't need to change out my gear. I only have a few hundred miles on my engine and don't want to run it anymore if I have the incorrect gear.
Thanks
John
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Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (theandies)
NO ONE SO FAR HAS REALLY ANSWERED MY QUESTION; THAT IS, WHAT IS MELONIZED?
I ASSUME THAT NON MELONIZED MEANS ITS PROBABALY A BRASS GEAR, WHICH WOULD BE A BAD THING IN THE 502
MELONIZED I GUESS MEANS ITS NOT BRASS, AND COULD BE EASILY CHECKED BY JUST SCRATCHING THE SURFACE OF THE GEAR. IF ITS BRASS, IT WILL SHOW AND SCRAPE OFF EASILY. IF ITS NOT BRASS,, IT WILL BARELY SRATCH
SOUND ABOUT RIGHT?
I ASSUME THAT NON MELONIZED MEANS ITS PROBABALY A BRASS GEAR, WHICH WOULD BE A BAD THING IN THE 502
MELONIZED I GUESS MEANS ITS NOT BRASS, AND COULD BE EASILY CHECKED BY JUST SCRATCHING THE SURFACE OF THE GEAR. IF ITS BRASS, IT WILL SHOW AND SCRAPE OFF EASILY. IF ITS NOT BRASS,, IT WILL BARELY SRATCH
SOUND ABOUT RIGHT?
Melting Slicks
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From: CA
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (MELVIN)
Melvin - You can easily melonize your dist. gear at home.
Just heat the gear with a torch to roughly 1500 Deg. F
While the gear is red hot, quickly thrust it into a melon. Try to do this in one swift movement. It may take a little practice, though. Watermelons work good. You could probably use a cantaloupe, but I have no experience with this type. Just make sure you use caution as sometimes they will explode.
Good luck
:yesnod:
[Modified by 71coupe, 3:27 PM 9/21/2001]
Just heat the gear with a torch to roughly 1500 Deg. F
While the gear is red hot, quickly thrust it into a melon. Try to do this in one swift movement. It may take a little practice, though. Watermelons work good. You could probably use a cantaloupe, but I have no experience with this type. Just make sure you use caution as sometimes they will explode.
Good luck
:yesnod:
[Modified by 71coupe, 3:27 PM 9/21/2001]
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Brett Foote
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From: In Dreams There Is Truth Ohio
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (71coupe)
Melvin - Watermelons work good. You could probably use a cantaloupe, but I have no experience with this type. Just make sure you use caution as sometimes they will explode.
Good luck
:yesnod:
Nope, you're wrong, big time. DO NOT USE CANTELOPE, USE WATERMELON.
Watermelon has the special liquidity to temper the gear after it has been heated to 1500 F. Think you may need a torch. The old bunson burner, don't think ya can have enough heat.
John, your crate engine came with the distributor. FYI, all GM distributor gears have all been stuck in the watermelons. Yours, mine, all of them, even your and my old 427. That is The General's way of saying, use our gears, do not use brass. Ah repeat, do not use brass gears.
John, thunk ya been readin' too much instruction sheets that came with da crate motor.
[Modified by 71coupe, 3:27 PM 9/21/2001]
Good luck
:yesnod:
Nope, you're wrong, big time. DO NOT USE CANTELOPE, USE WATERMELON.
Watermelon has the special liquidity to temper the gear after it has been heated to 1500 F. Think you may need a torch. The old bunson burner, don't think ya can have enough heat.
John, your crate engine came with the distributor. FYI, all GM distributor gears have all been stuck in the watermelons. Yours, mine, all of them, even your and my old 427. That is The General's way of saying, use our gears, do not use brass. Ah repeat, do not use brass gears.
John, thunk ya been readin' too much instruction sheets that came with da crate motor.
[Modified by 71coupe, 3:27 PM 9/21/2001]
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St. Jude Donor '03
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (theandies)
Thanks for the laugh guys, I needed that. :lol:
John - I was concerned about installing my distributor in the new ZZ502, so I called MSD and gave them the part number for my tach drive MSD distributor. They assured me that it was indeed a melonized gear.
Melvin - Good luck with these guys, they are in rare form today. ;)
Dave
John - I was concerned about installing my distributor in the new ZZ502, so I called MSD and gave them the part number for my tach drive MSD distributor. They assured me that it was indeed a melonized gear.
Melvin - Good luck with these guys, they are in rare form today. ;)
Dave
Drifting
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Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (MELVIN)
MELVIN------
A melonized distributor gear is a gear which has been specially hardened and surface-treated so as to be compatible with a steel camshaft core. Steel camshaft cores impose special requirements on distributor gears. Most flat tappet camshafts, mechanical and solid lifter alike, are manufactured from ductile iron camshaft cores. The stock GM distributor gear, GM #1958599, which was is used for most pre-87 flat tappet engines is of material and heat treat to be compatible with ductile iron cores. This gear is NOT compatible with steel camshaft cores used for 87+ GM roller cam engines.
You are wise to be concerned about the use of the proper gear and you are wise to heed the instructions supplied with the engine. I can ABSOLUTELY ASSURE you that the instructions are NOT designed to trick you into unneccesarily purchasing a melonized distributor gear from GM. Those instructions are VERY important. They may not be important to FOOLS, but they're important to wise folks.
By the way, GM has used the melonized gear on EVERY roller-cammed PRODUCTION and SERVICE engine which they ever made. Neither GM nor ANY OTHER ENGINE MANUFACTURER uses a brass distributor gear on a PRODUCTION engine. ZERO. Absolutely NONE.
A melonized distributor gear is a gear which has been specially hardened and surface-treated so as to be compatible with a steel camshaft core. Steel camshaft cores impose special requirements on distributor gears. Most flat tappet camshafts, mechanical and solid lifter alike, are manufactured from ductile iron camshaft cores. The stock GM distributor gear, GM #1958599, which was is used for most pre-87 flat tappet engines is of material and heat treat to be compatible with ductile iron cores. This gear is NOT compatible with steel camshaft cores used for 87+ GM roller cam engines.
You are wise to be concerned about the use of the proper gear and you are wise to heed the instructions supplied with the engine. I can ABSOLUTELY ASSURE you that the instructions are NOT designed to trick you into unneccesarily purchasing a melonized distributor gear from GM. Those instructions are VERY important. They may not be important to FOOLS, but they're important to wise folks.
By the way, GM has used the melonized gear on EVERY roller-cammed PRODUCTION and SERVICE engine which they ever made. Neither GM nor ANY OTHER ENGINE MANUFACTURER uses a brass distributor gear on a PRODUCTION engine. ZERO. Absolutely NONE.
Pro
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From: Hamilton, ON, Canada
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (MELVIN)
Good to see so many people with a sense of humour, but to answer your question directly, Melonizing is a carbonitriding process that hardens the surface of a steel part. Specification of a Melonized gear means the gear is steel, not brass, & it has a hardened surface (usually 0.002-0.003" thick) to resist wear. There are a number of proprietary case hardening processes, each with its own name, but they all do essentially the same thing-provide a hard surface-usually accomplished by soaking the part in a molten bath of cyanide salts. My crankshaft is Melonized & I researched the process a no. of years ago.
Team Owner
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From: Virginia USA
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (Rolling Thunder)
John - I was concerned about installing my distributor in the new ZZ502, so I called MSD and gave them the part number for my tach drive MSD distributor. They assured me that it was indeed a melonized gear.
Thanks again
John
P.S. The rest of you guys crack me up.....stick your gear in a melon!!! :crazy: :crazy: :crazy: :crazy: :crazy: Thats good :lol: :lol:
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St. Jude Donor '03
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (theandies)
John - 8572 is the correct part number. BB and SB are the same. If you'd like to contact them yourself, their tech support number is:
(915) 855-7123
or you can email them with your questions and concerns:
msdtech@msdignition.com
Good Luck
Dave
(915) 855-7123
or you can email them with your questions and concerns:
msdtech@msdignition.com
Good Luck
Dave
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From: Virginia USA
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (Rolling Thunder)
Thanks for your help Dave. I'll take your word for it. I've only had the engine installed for about 4 months so I am just going to go with it. How is your performance with that 502? You must smoke the :reddevil out of your tires. I almost went with that engine but my wife vetoed it on the price. Is it easy to work on and was your car originally a big block? Just wondering.
John
John
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St. Jude Donor '03
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (theandies)
You're welcome John. I have not done any tire smoking yet, still too many things to do. I assure you that will come later. :D The car was a 270hp 350, 95% original when I got it. It's been what seems to be a long drawn out process, but that's my fault for trying to do too many things at once. :rolleyes: From my signature above, you can see that the NCRS would laugh me out of town. 
BTW, I forgot to ask the wife for permission to buy the 502 (or the other stuff) and bless her heart, she has never once complained or even asked how much it all added up to. :blueangel:
Dave
BTW, I forgot to ask the wife for permission to buy the 502 (or the other stuff) and bless her heart, she has never once complained or even asked how much it all added up to. :blueangel: Dave
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From: In Dreams There Is Truth Ohio
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (Joe Lucia)
MELVIN------
They may not be important to FOOLS, but they're important to wise folks.
They may not be important to FOOLS, but they're important to wise folks.
Le Mans Master
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From: Raleigh North Carolina
Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (GDaina)
MELVIN-
I THINK YOU JUST MIS-READ THE INSTRUCTIONS. THE 502 CAM REQUIRES A "MELVINIZED" GEAR.
JUST POP IT IN YOUR MOUTH FOR ABOUT A WEEK AND THAT WILL THOROUGHLY MELVINIZE IT.
NO PROBLEM.
YER PAL
TOM
I THINK YOU JUST MIS-READ THE INSTRUCTIONS. THE 502 CAM REQUIRES A "MELVINIZED" GEAR.
JUST POP IT IN YOUR MOUTH FOR ABOUT A WEEK AND THAT WILL THOROUGHLY MELVINIZE IT.
NO PROBLEM.
YER PAL
TOM
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Re: 502 CRATE NEED DISTRIBUTOR WITH MELONIZED GEAR? (Joe Lucia)
Melvin, I believe GM part # 10456413 gear, fits the late model electronic distributors with a .500 shaft diameter. 1974 and earlier distributors use a .491 shaft. I ended up using a bronze gear in mine, I couldn't find a melonised gear to fit a .491 shaft
