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...I believe the Distributer Gear is Originally Lubricated by 'Splash' thrown up from the Timing Chain!
When I built My Engine, I followed a recommendation, and drilled a .030" Orifice through the Center of the OPPOSING, Oil Gallery Plug! It Squirts a Constant Stream of Oil Directly Into the Meshing Distr. and Cam Gears! Yes! It does drop the Pressure Gauge Reading, But it's a very small amount. I can tell You the Gears Run Silently!...
Clevelands don't have an inherent problem with distributor gear failure. The gear is normally a part of the motor taken for granted, it does what its designed to do just fine, it doesn't need to be re-engineered. There are countless 30 to 40 year old Cleveland powered vehicles on the road, with abused and tired motors, but never a problem with the distributor gear. If a 351C is having a problem with its distributor gear its because (1) it has been assembled wrong, (2) poor quality parts have been used, (3) incompatible parts have been used, (4) the wrong lubricants have been used, (5) the wrong parts for the application have been used, or (6) some aspect of the motor has been altered unsuccessfully.

The distributor drive gear needs the additive ZDDP, even if the motor is equipped with a roller cam you still need to use motor oil with ZDDP. The lack of ZDDP could lead to rapid wear of the distributor gear.

Distributor gears need to be manufactured of materials compatible with the camshaft core, in my mind that means either heat treated iron or heat treated steel. The oem gear is compatible with iron camshaft cores, but certain roller cams, like the Crane hydraulic roller cams, have steel cores and need to be mated with steel distributor gears (available from Crane). Some replacement iron distributor gears are poorly manufactured and wear very quickly, such as the gears you might purchase over the counter from an auto parts chain like Auto Zone, Kragen, etc. Bronze distributor gears are a race engine thing, they are designed for engines that are torn down frequently or only see limited mileage in a season of racing (trailered drag race cars). I wouldn't expect a bronze gear to last very long, but I know some guys who are using them on the street and getting away with it. I advise against it however.

Some cam manufacturers think high volume oil pumps can lead to rapid wear of the distributor gear, Ron makes a good point, very heavy motor oil could do the same thing. If the gear is installed on the distributor shaft improperly it could be binding against the engine block making the distributor difficult to turn. If the oil pump drive shaft (intermediate shaft) is too long it could also create binding and make the distributor difficult to turn.

Last edited by George P
I was breaking in a new engine and after 20 min on the dyno, the distributor gear was done - three teeth completely gone and the rest sharpened to points. The cam also went flat. I had installed my old Duraspark distributor that was taken from another engine. This engine was a 14 year old build that had never been started - took my chances.
After this incident, a friend and I took it apart. We changed the bearings, new camshaft, new standard oil pump(not high volume as was installed initially) and are in the process of reassembling. I purchased a new "ready to run" MSD distributor with drive gear. For break in, I bought the Brad Penn break-in oil. All surfaces are freshly lubed and a Kevco 9 qt pan is installed.
I am trying to ensure that the distributor gear is not detroyed prematurely. Any suggestions would be appreciated.
I purchased a new "ready to run" MSD distributor with drive gear.

I believe your MSD distributor gear is made of an alloy which is only compatible with OEM iron cam cores and ductile iron cam cores, and most likely incompatible with 8620 steel cam cores commonly used for aftermarket roller camshafts. Check with MSD to be sure!

What is your cam? Check with MSD and your camshaft manufacturer for specifics on materials and compatibility to avoid having to do this all over again after the next break-in run.
Install the distributor in its hole with the timing cover off & the timing chain removed. Slide it all the way in, install & tighten the distributor clamp. Now grab the shaft above the gear and check it for "wiggle room" up and down. If there's no "wiggle room" then something is binding. If it has "wiggle room" next install the oil pump and the oil pump drive shaft. Tighten the bolts all the way. Grab the oil pump drive shaft and check for wiggle room, if there's no wiggle room then something is binding. If the distributor shaft & oil pump shaft both have wiggle room then it will be a good idea to disengage the oil pump from the distributor & turn the oil pump by hand to see how hard it is to turn, you should be able to turn it by hand (use the hex shaft to turn it).

Cam lobes and lifters are splash lubricated, there's a lot more oil splashing about at 2000 rpm than there is at idle, so when you first start the motor run it immediately to 2000 rpm and cycle it between 2000 and 4000 rpm for about 5 minutes to seat the rings (do this only if you've replaced the rings), but don't let the revs drop below 2000 rpm. After 5 minutes just hold the speed steady at 2000 rpm for another 15 to 20 minutes. That should be enough to break-in the cam & lifters.

i've found that an undersized distributor housing or enlarged distributor hole in the block will allow the housing to cock to one side when the hold down clamp is tightened, causing the distributor shaft to bind in the pilot hole down in the block and effectively locking up the dizzy shaft

as George describes i did a mock-up with a bare block on a stand and 2 different distributors. upon finding that the shaft was bound up i progressively disassembled a stock points distributor looking for the culprit, i ended up with a bare housing and bare shaft that wouldn't turn with the hold down clamp tight

prior to disassembly, without the hold own clamp both distributors turned free and showed up/down oil clearance to the block ledge but when i BARELY snugged down on the clamp bolt the shaft wouldn't turn. then i loosened the clamp, removed the shaft from the housing still in the block and re-snugged the clamp. the shaft would not drop back in all the way, it stopped at the ledge in the block for the pilot hole that the bottom of the shaft rides in.

then i loosened the clamp and the shaft dropped right in

this finding is in addition to checking the installed gear height on ANY distributor, absolutely do not trust that the gear is set correctly. replacement gears used to be sold with a 'through hole' supposedely in the right place, now they are sold with only one side drilled in the totally wrong place or none at all

bottom line is that a bound up shaft for whatever reason will cause enough resistance to wear down a distributor gear AND the cam drive gear very quickly
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