I wish my engine would quit eating the distributor gear.....

jaredgoodwin

New Member
Sep 29, 2004
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Engine: 1969 351W
So over the last month and a half I have had ongoing problem with my distributor gear(s). For some reason, my distributor gear is wearing badly. The first time this happened, I replaced the distributor (still under warranty), and within two weeks I had the same problem. After two distributors, the cam gear was shot. So two weeks ago, I tore the engine apart. I replaced the high volume oil pump with a standard volume in an attempt to reduce the load on the gears (Tightend the bolts with distributor installed to ensure everything was lined up). I installed an ARP driveshaft (and I checked for block to shaft clearance as well as shaft to distributor). I replaced the camshaft (Summit cam flat tappet SUM-3601). I am using a (third new one) duraspark II distributor from a mid 70's truck. I used moly lube on both the cam gear and the distributor gear. After a little over a week and a half, I checked my ignition timing (indicator that the gear is wearing, timing backs off as gear wears), and it was off by 5 degrees. I pulled the distributor and the gear is showing some significant signs of wear. The gear had oil on it when I pulled it out.

Any ideas? The wear pattern on the gear looks fine (as far as teeth engagement depth). I think that insufficient oil is getting to the gear. I have heard you can drill a .030" hole in the plug under the cam sprocket to increase the oiling. I am using a cast iron gear on a hydraulic flat tappet camshaft. The engine has approx 8K on it, for the first 6k I had no problems. Around 6K I took it to school to dyno it and it overheated, blew a head gasket. Before I figured out the head gasket was blown, I tried a different distributor, didn't make a difference so I just left the new one in (kind of regret that now, but hey it was free). That distributor lasted maybe 1000-1500 miles before the gear ate all the way through. I replaced it and drove it for a week. After pulling it to check it, it was not good, I parked the car to pull the motor. Replaced everything listed above, and here I sit with another chewed up gear.

Any thoughts or ideas will be appreciated. Let me know if you need more info.
 
65fastback2+2 said:
well besides the fact it may not fit, why else would it not work??? Even such places as crane cams have told people if their dizzy gear is getting eaten up to switch to a steel cam gear. er am i not thinking


switching to a steel distributor gear will eat up the gear on the cam. i noticed you said you were using a duraspark from a mid 70's truck, what engine did it come from? in the mid 70's the only 351 in trucks was the 351M if you are using a 351M distributor then that is your problem, you need to get a distributor for a mid 70's passenger car with a 351W instead.
 
Yes, the bronze gears do tend to wear quicker, that is the idea. They wear rather than "chip" and put all those "chips" into the motor. The normal wear of the bronze gear is picked up with the other bad stuff (oil, gas, etc) by the oil system and does not harm the motor.

Just check the gear during your normal play time with the old girl!

HistoricMustang
www.historicmustang.com

kenmiles2.jpg
 
HistoricMustang said:
Yes, the bronze gears do tend to wear quicker, that is the idea. They wear rather than "chip" and put all those "chips" into the motor. The normal wear of the bronze gear is picked up with the other bad stuff (oil, gas, etc) by the oil system and does not harm the motor

what about the carbon composite gears? Can anyone intelligently opine on those?