2nd distributor pin shear in less than a year

well I relived an unpleasant experience yesterday--the General's distributor pin sheared at highway speeds.  Again.  This is a rebuilt distributor.  This time it didn't damage the housing itself, so a mechanic that specializes in Fords/Ford 300s is going to show me how to replace the roll pin.  I
Then we are going to do a compression check.  Maybe a leakdown too.  But could my timing chain be old and slipping or something, causing issues with the distributor?  

I am having a hard time visualizing why this would keep happening.  We checked the movement of the oil pump once I had the distributor out and it was fine...thankfully.  My oil was surprisingly low considering I had changed it and the filter not 1000 miles ago.  But Not Dry!  And no visible leaks, I am always loking underneath.  No water in oil either.  First time using a K n N filter, I always used the Motocraft FL1A but recently heard they are not being made by Ford anymore so tried something else.  I changed the oil, put another Motocraft filter on, and have kept the old filter/oil to examine for metal shavings...

I should also say I have been having carb issues for some time that I haven't been able to figure out.  But it runs ok, getting about 15 mpg...so rather than messing it up worse I have been leaving it for now.  

Any thoughts on the dizzy pin would be appreciated.  I have looked through the forum pages and it seems that oil pump or low oil/ie excessive friction is the main culprit.  Could it just be bad luck with reman distributors?    Thanks everybody.  Every time I post I find my old posts and the responses and realize how much more I understand than the last time haha.  

I broke them regularly on my 390 in my 1977 F150. Only thing that normally shears them is something binding the oil pump. A double pin (smaller one inside the normal one) may help. On a 300, if it still has the phenolic cam gear, it could be starting to fail. Other source of debris are the valve stem seals. Best to have him drop the pan and check the pump and screen and look for anything in the pan that could be getting pulled into the pump.

Two things come to mind from long ago:

1. Has the oil pump ever been changed to a high volume one?

2. Once a person whom I trust mentioned replacing the distributor drive pin [in a 300 cubic inch quarter mile racing engine] with an appropriately sized welding wire.

We doubled up on roll pins but when we tried to do timing the cams not moving 😭😭

Ok, now I know what was stopping your oil pump, cam gear teeth. If you don't mind a slight whine, use a steel cam gear.

Are you reusing the same gear?

If Rock Auto still has some left, they were closing out some fine tooth steel sets at a bargain basement price.  That should reduce the whine some.

I am completely new to cams.  Is there anything else I should know when ordering parts?  Or when getting into this project?

just 2 cents. when I rebuilt the 300 in my first truck, I eliminated the phenolic gear and installed a steel set figuring I could accept the noise for reliability. that was twenty years ago and it's still one of my daily drivers and i have never noticed any noise to date. there may be differences in brands but I see no reason to use anything else.

I am still confused.  I thought the steel and aluminum ones were for the later fuel injected 300s?  only options on rock auto for my make/model are fiber (no thanks) iron and aluminum.  I am concerned about noise, but reliability is my priority.    

Right now I am about to pull the plug on a Melling cast iron set / Fel Pro gasket (with the seal, for after 5-15-85) and a Mahle 2pc cork/rubber oil pan gasket.  Are people using the word "steel" interchangeably with "cast iron"?

Also the timing gear set doesn't come with a new key.  Is that an issue?

not coming with a new key is no issue at all, re use the original unless it looks sheared and that is highly unlikely. yes , calling one steel vs cast iron is likely thought of as the same in this case. not in the case of the cam yet in the cam gear yes. often the cast iron will have an obvious shape of having been cast in a mold and milled into finished shape much like the block itself but even cast iron is a form of steel yet a little less ductile.