Here are some pics of the gear wear at the bottom end of the teeth and the pad at the bottom that I thought was suppose to ride on the block. I just put a used pin in for measuring.
 Should the teeth wear be more in the middle of the gear?
 Should the bottom pad be more shiny? Maybe it's not riding on the block and the roll pins are absorbing too much torque from the cam gear?

There are two different type of roll pins. There is the standard type and the type that looks like a carpet that is rolled up. Meaning multilayered this is the type msd distributor come with. The wear on your gear does look to be on the low side, I would take a flashlight and look at the camshaft gear itself just to be safe. I have seen thicker oils give the stand/regular roll pins a problem. Some guys used to drill a very small hole in the front oil plug directly behind the distributor gear. This would help with premature wear a .030/.040 hole is good.


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The plug is located behind the timing chain. So you would need to remove the timing cover and chain to access it. Remove it drill it clean it reinstall it. 20/50 can be thick on start up once it is warm it should be fine but if you decide to run it up at a higher rpm while the oil is cold it can build a lot of oil pressure. The more oil pressure the harder it is on the distributor pin.


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There are two different type of roll pins. There is the standard type and the type that looks like a carpet that is rolled up. Meaning multilayered this is the type msd distributor come with. The wear on your gear does look to be on the low side, I would take a flashlight and look at the camshaft gear itself just to be safe. I have seen thicker oils give the stand/regular roll pins a problem. Some guys used to drill a very small hole in the front oil plug directly behind the distributor gear. This would help with premature wear a .030/.040 hole is good.

The best spiral-wound pins do offer slightly more load bearing capacity than the standard slit pins, but only perhaps 5%.  A 5% difference in pin strength is not likely in itself going to make the difference in a pin shearing, and in fact if you are shearing pins then there are other more significant culprits.

The typical range in engine oil viscosity as typically used in these engines is not enough to be a "make or break" deal in shearing pins (ie, from 10W-30 to 20W-50), and in fact the oil pump's bypass piston setting (ie, peak oil pressure) plays a far greater roll in how much load a distributor gear may be subjected.

An extra splash or squirt of oil to the meshing cam and distributor gears--particularly the bronze distributor gears--can substantially diminish tooth wear and increase gear life indeed; unfortunately it is not going to do anything to help prevent roll pin shearing.

Judging by the tooth wear focused around the lower third of the gear, I think it would be wise to check distributor gear positioning on the shaft and also the thrust clearance.

 
 Measured the gear at: 4.035  with end play pulled,
                                  4.012  with end play pushed in.

 Factory wants  between 4.031 and 4.038. I'm perfectly in the middle.
 Wonder why my gear is wearing not in the middle and roll pin breaking?

Measured the gear at: 4.035  with end play pulled,

Factory wants  between 4.031 and 4.038. I'm perfectly in the middle.
Wonder why my gear is wearing not in the middle and roll pin breaking?

After measuring and setting the gear position on the distributor itself, you need to physically check it in the block.  All blocks are not the same--some may have wear on the thrust pad, for example.

 Have a new Davis Unified Marine Distributor, aka  DUI. I had to send it back because the housing was chipped and cracked, and the cap wouldn't fit right. OK, a week later, it comes today and everything looks cool, except now the gear must be bottoming out on the block because the housing won't touch. Spending almost $400 on a new Dist. because of a broke gear pin is turning into a nightmare. I researched the heck out of this company and couldn't find anything bad. It looks like I might have to send it back a second time.