Ok ! Do an online search on melonized and you will find out it's basically case hardening.
The gears on the cam are hard steel like the rest of the cam. You should not have the problem with the Melonized gears. There were alot of valvetrain problems with the earlier Roller motors like yours. This is just another one of them. Believe it or not, Gm and Mercruiser learn along the way. Sometimes in this process Mercruiser learns and Doesn't get the fix right away from GM or the right hand doesn't know what the left hand is doing. The 10456413 gear is too big for My Delco Voyager EST distributors. I'm going to buy a Msd 08360 for a 502 I'm doing. I think after a certain time all the GM gears were melonized. I wish I knew what markings or details other than color came into play. BBB

Correct part number
 

ACDELCO 10493532 Silver gear. Rock Auto has them $37
That Msd number was a Whole Dist . I may still try to get a Msd Gear at the speed shop if I can get one that fits.
I have to Mic the shaft. It's late I am tired, Ran broke in and finished another installation today.

Wow, way to bring back a post from the past. ;)

Thanks for the update though. I've been contemplating replacing the dizzys with MSD units for a while now, but have otherwise been running stock MerCruiser distributors.

FWIW: I replaced the bronze gear with a factory replacement gear and haven't had any problems in 8 years. :)

I've got a pair of MSD billet distibutors in the swap shop.
MC

Hey Guy's Im new here. I buy 1987 aquasport tournament master with twin mercruiser 454 straight shaft engines. When i start drive from the long island to the Brooklyn, somewhere in channel i hit bottom because the shallow of water. It was noise and also lost half of oil from the left engine. After that cant start engine because no more spark in distributor. I mean when i take out distributor from the engine i see that there isn't cam gear in it. Anybody knows what happened and whats the solution?

I read that cam gear break causes may be high oil pressure/ thick oil / cold engine with high RPM or all of this together

SOS! Please help if anybody knows anything about my case.

better pull that engine and take it apart. Those pieces went somewhere. I agree all the above. Don't need more than 10-40 weight and oil takes like 10 min to get up to temp. If your lucky you will just have to clean the pan. If the pieces got between the roller lifters there might be damage. Pull pan check bores ,piston skirts and oil pump. Take oil pump apart. Could be damaged

Thanks. As i know gesr replacement is possible from the bottom pan side but for me much easy if i take out apart because of the weight of engine. Its big block so should be around 1300 lb with transmission. Do u know whats the just block weigh if i take out everything except it.



Most important thing is that distributor shaft or gear are without any scratches. If i lost cam gear why didn't damage distributor ?

Is it possible to see cam gear from outsidr or it just located under hole.

Gear is on distributor shaft and camshaft. Camshaft gear may be damaged also. Which means pull the can. You can see if can gear is damaged by looking down thru distributor hole and rotate engine to see th whole gear all the way around it. Something happened don't take anything for granted.

I know when you buy a zz502 or ho454 cam thew say you hafta buy the melonized gear. That may be true of EVERY stock roller GM cam. even sub-500 lift ones. You would think in that case every boneyard distributer would have the hard gear.

You may want to take some pictures and post them of your distributer. You may want to pay for the membership so people can see and help you.