distributor gear gone in 500 miles

[rojam18801]

when i built this 347 stroker, was told to use a bronze dizzy gear and replace it once a year. it has been over a year but only drove about 500 miles since the build. teeth were worn to knife edge and failed. it just dont seem right to me. anyone have any idea why it failed so fast. i replaced it with a hardened steel gear....the old trucker

[v8ranger]

Hey, long time no hear from in the place old trucker. What I think, and dont hold me to this, the bronze is to soft for a ratical cam. Or the bushings in the distributor are bad. I would think you should be ok with a harder gear now, but check and make sure there is no play, side to side in the distributor. Thats just my opinion.

[Grumpy]

what cam are you running ??? i mean what is it made of ?? like a "soft" metal or a "hardened" metal? cuz that DOES make a difference .. like on a Mustang HO cam ... you have to run one kind of distributor gear ... a 'hardened" one compared to a older cam which you have to run a "softer" gear ..IF my memory serves me right but it might be the other way around ..... best thing to do is call Summit and give them your cam specs ( name brand and part number and lift and all that ) and the distributor you are running too ....and they can tell you which distributor gear you need to run. Because if it is wearing it down to a knife edge then you got the wrong gear on the distributor and it will eventually do the same to the cam gear too. if you run a "soft gear on a "hardened" cam then it will wear it down to a knife edge then start on the cam gear too... which will entail a cam swap in the future.... then again .... if you run a "hardened" distributor gear on a "soft" cam the same thing will happen . So best to check into it with a speed shop like Summit or Jegs and get the correct answer over some fly by night place or a place that just "guesses" on what you need or should run... then in the long run cause problems... cuz just think that IF you hadn't caught that gear in time ... then you would have had all kinds of metal going all thru the engine if it had broken some teeth off or broken in half ... that could DESTROY your cam in the process too!!!... so i would call them and give the part # and name of it and all ,.,, roller... hydraulic or solid ... ALL that info will be needed before they can give you the correct answer ..... Good Luck


BTW... i got the engine and Tranny and all out of the Mustang now and all cleaned up and fixing to tear it down to replace the intake and fuel rails and injectors and do some work on the TKO too .... so it "should" be going into the Ranger here soon .... lol..... ok .. im out for now.. Peace and GL on the gear

[ranger50toy]

Are you running a high volume oil pump? These are known to break pump shafts and could contribute to excessive gear wear.

[rojam18801]

sorry guys been out of town for a week. comp roller cam, gear driven. 306 dur, 612 lift, roller rockers.regular oil pump. dizzy is mallory, new with 500 miles too. got a lot of bronze in oil now too. dont like that at all...the old trucker

[Dave]

Been thinking about how much stuff got pushed thru the engine. I guess the only good news is that brass is soft and doesn't do as much damage as a hardened steel gear would have. Plans on flushing the motor out, cleaning even the lifters and such?
Dave

[fordmike1]

If you are running a steel cam (roller) I would run steel gear on your dizzy. If you have a cast cam (flat tappet) then you should run a cast or bronze gear. I ran a bronze gear on a cast cam for many years in my Camaro Big Block with zero issues ever. Put a steel gear on your dizzy and call it good and as for all the metal in your engine now drain your oil and run a couple of cheap new quarts of oil thru it and then fill it back with good oil and a new filter and you should be just fine.

[Dave]

Just saw something in the latest Car Craft and thought of your problem. They call for break in lube on the gear. Here some comments from other sites on the same problem.
Dave

Excessive Dizzy Gear Wear

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Sirs,
I have a 351W with PN8584 MSD Dizzy. After 500 miles or so, the dizzy gear wore down and disintigrated causing the cam to break teeth as well. I changed the cam to a Crane solid, and sent my dizzy back to MSD for a new iron gear. (For a solid flat tappet) After three 1/4 mile passes, the gear is once again ready to fail as it has wore excessively. Yes, I broke in the Dizzy gear with the supplied Comp- brake-in grease. I also broke in the cam with Rotella T 30 weight and put the GM EOS on the lifters. It can't be because I run a high volume oil pump. What is the problem? I now have to send the dizzy back to MSD for another gear. Thanks,

Mike


#2 12-12-2007, 07:57 AM
msdtech22
MSD Tech Join Date: Jun 2003
Posts: 4,434



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When breaking ANY distributor gear in for the first time when using a high volume oil pump you need to use a 5 weight ONLY racing grade 'break-in' oil and run the engine at idle for 15-20 minutes. Use of the 'break-in' lube alone is not sufficient.

When breaking that gear in using a thicker oil, (higher viscosity rating above 5 weight, multi-viscosity, or synthetic) there is extra pressure against the shaft and gear cousing it to possibly move up and down and side to side causing uneven gear wear. Once this begins it is impossible to reverse this proces and the gear will tend to fail.

There should have been a tag on the distributor when you bought it explaining this.

If you need a more indepth explaination, please call the tech line at 915-855-7123 and we can discuss at length.
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MSD Tech Line: 915-855-7123

msdtech22
MSD Tech Join Date: Jun 2003
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Try breaking it again. Your Rotella oil should be fine as far as you stay with a single weight oil such as a thirty weight oil. If you don't want to try that then go to a racing supply shop and look for a 'racing grade mineral oil at single weight' that should have all the additives you will need to protect all areas of the engine.

When you put the distributor in, pack it very liberally with black MOLY-LUBE. Our cam gear lube is good but the Moly-Lube will work better.