Polymer distributor gears - are they good/strong ?

I have a severe dist gear wear problem with my 393. I am running a cast core Comp Cams hydraulic roller cam and standard casr driven gear.And a HV pump. The gear lasts max 2000 miles before really needing replacing.And even moderate wear is bad for the timing since the spark advance does not work accurately.
When I contacted Comp Cams they told me to get one of their new fancy polymer gears but they are about 100 bucks a piece[img]/phpBB/images/smiles/icon_eek.gif[/img]
Has any of you used them? I can of course go back to std volume pump but it would be much easier just to change the gear.But - I dont wanna spend 100 bucks in a tiny piece of s.. plastic if it doesnt give any benefit compared to std cast gear.Anybody used them?
I have also a brand new MSD distributor waiting installation and I dont want to ruin the new gear in that.
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You'll get conflicting reports from the techs at Comp as to what to run for a distributer gear... but my bet is the cam core is a type of steel, and you'll need MSD's STEEL gear. It costs around $69, and is what people have had the best luck with.

It's MSD part number 85834

Go here for a discussion on your situation...

http://www.clubcobra.com/t42142-15-1.html

This summer, a buddy of mine (with a hydraulic roller in a 351W block) was visiting in town with his mustang. He was using a bronze gear. After around 2000 miles, his car quit running because the distributer gear quit turning. The gear was GONE! I ordered the 85834 gear NEXT DAY AIR, installed it, and he was back in business. (he said his car had been running poorly for a while) So far, so good... The car is running great! [img]/phpBB/images/smiles/icon_smile.gif[/img]

Good Luck!

_________________
Mike Burch, 66 mustang real street
302 4-speed 289 heads, 10.63 @ 129.3
http://www.mustangworks.com/cgi-bin/moi-display.cgi?220
http://www.fortunecity.com/silverstone/healey/367

<font size=-1>[ This Message was edited by: n2omike on 11/25/03 6:48am ]</font>

Thanks for the comment and link Mike. Looks like nobody( even the manufacturers)knows actually the answer.So far those Cobra guys seem be on the right path with steel gears. I am still hesitant : what if the gear eats up the cam ?[img]/phpBB/images/smiles/icon_eek.gif[/img]
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Ville...

The distributer gear for that application is pressed on.

It will need pulled off with a gear puller, then the new one pressed on in it's place. Do not hammer the gear on there, and be sure the have the top of the shaft supported so there isn't a load against the bearings. (just remove the rotor, and set the shaft against something solid)

MSD recommends 4.000" +/- 0.005" This is measured from where the housing sets in the block to the bottom of the gear. Some have found this setting to be a little deep, which caused the gear to wear against the block.

I would recommend looking the gear over carefully to inspect for unusual wear on the bottom, then if it's OK, measure the depth of that current gear.

MSD recommends pressing the gear onto the shaft at the proper depth, then drilling a new hole through the gear and shaft, and installing a new roll pin. As a first try (you can always take it back apart) I lined everything up and simply re-used the old hole in the distributer shaft. The depth worked out just fine. (just a little shorter than spec)

The gear itself only comes drilled halfway through, so you still have to drill it the rest of the way once it's put on the shaft.

Good Luck!
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I am thinking putting the std volume oil pump in the engine..that will solve the problem for good.Bearing tolerances are not that big, I put the HV pump there in the first place just as an extra insurance. Stock pump with slightly shimmed spring should do the trick.

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Changing the gear is not as hard as it sound. Any puller can pull the old one off, and the new one could probably be tapped into place as long as the opposite end of the shaft was properly supported.

Install it at the proper height and be happy.

Oil pressure is what puts a load on the pump. Shimming a stock pump to produce more pressure won't help your cause any.

Good Luck!
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Yes - pressure...and volume.Arent these the factors which dictate the amount of horsepower required to drive the pump.
My oil pressure 2000 rpm up is 65 PSI.
I have used slightly shimmed stock pumps before with about same pressure( 65 PSI) and no problem.
Even though the extra volume pumped by the HV pump mostly only circulates in the oil pan because of the overpressure spring,it is clear that this requires more power than with a smaller stock pump.But how much - go figure..
Perhaps the metafora about a straw and camel´s back applies here.The extra power required to drive HV pump being the straw..
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are you sure your cam isn't billet, like most roller cams? it it is,,,get the Ford Motorsports steel gear. it will last.

I have asked Comp twice- they said its a cast core..
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Go re-read the 'clubcobra' link above, then make your decision.

I realize, you are like me, in the fact that you don't take advice blindly from ANYONE. YOU must be able to see it in your OWN mind. (the reason you haven't tried jet extensions yet) It's the reason your car works as well as it does. You're smart, and have worked your way through several combinations, LEARNING and UNDERSTANDING along the way.

How many different manufacturers do you think there are for Ford hydraulic roller cam blanks? Comp Cams simply buys these from a big supplier and grinds their profiles onto them. It's probably the same supplier ford uses... and Ford uses steel gears on their hydraulic rollers. This reasoning, along with the clubcobra post are what convinced me to use a steel gear on the 393 stroker I had to work on a few weeks ago. He drove the car home (eight hours) and had no problems. He checked it after getting there, and everything is doing fine.

Good Luck!
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