Ford FE distributor drive gear and pin
 

I have been down this way a while ago. The recent experience is trying. The distributor drive shaft is 1/2" ID. The drive gear boss (where the pin is installed) is 3/4" ID Original equipment was a split ( slotted) spring pin 1/8" x 3/4" worked with original oil pump and usually warm oil. It's the drag of the Melling high volume oil pump with cool oil that did my original split spring roll pin in. I had great luck ( longevity) with the spiral coiled roll pin I installed 15 years ago.
I thought I had a problem but the spiral coiled roll pin wasn't the problem.. The distributor drive gear has 15 teeth. An odd number of teeth one pin hole. Installing the gear 180° out on the shaft, isn't the same. My mistake 15 years ago. It was a problem, My Mallory distributor has a mechanical tack drive and doesn't allow much movement of the distributor housing for timing adjustment. So I moved wires around the cap and reset the distributor drive gear teeth and cam teeth to get things back in to timing. 15 teeth = 24° per tooth each spark plug wire terminal is 45°. I didn't know what to look for when I tried to reinstall the drive gear on the shaft. Recently I suspected the drive gear pin had failed. I didn't know But the new spiral coiled roll pin didn't break. Back fifteen years ago, I used a longer spiral coiled roll pin. The pin had beveled ends that tried to align the gear and shaft holes some as it went in. The pin was longer than the drive gear boss was wide, so I cut the excess pin off . That was a mistake. A little pin sticking out, what would it hit? But my cutting that excess pin off turned that pin in to a one time use. Square pin ends don't help align or fit anything. I mushroomed the pin making it junk.
What was I to look for as indicator for returning the drive gear to original placement ? I now want a source and number for purchasing new spiral coiled roll pin (s) not just one . I tried a quantity to buy a quantity what I thought was spiral coiled roll pins only to ended up with DOORMAN 623-046, which are slotted spring roll pins 1/8" x !' I swear 15 years ago the spiral coiled roll pin, I bought, were from MSD and came two to a package at Local auto parts store. Again 1/8" diameter x 1 inch long spiral coiled roll pin. would be great. I'll buy a quantity this time.

McMaster Carr has them.

Sounds like you're looking for some of these:
http://www.spirol.com/library/catalo...cldp-group.jpg

Coiled Spring Pin 1/8 x 3/4 SD 420 SS Oiled, Double Shear Strength Minimum: 1400 lbs
https://www.huyett.com/Products/Fast...50?searchText=

$0.75 each, minimum order qty: 3

Edit: Above 3/4" long, below 1" long

Coiled Spring Pin 1/8 x 1 SD Carbon Steel Zinc Clear, $0.33 ea, minimum order qty: 7
https://www.huyett.com/Products/Fast...00?searchText=

Coiled Spring Pin 1/8 x 1 SD 420 SS Oiled, $0.2929 ea, minimum order qty: 7
https://www.huyett.com/Products/Fast...00?searchText=

Mike;
FWIW, when I did my own engine I heard about this problem and I, too, have a Melling HV pump so I decided to solve it in advance. I went with 3/16" Chevy pins from MSD (I had to take the distributor out to dinner and get it drunk first!). I punched out the 1/8" pins, set the whole mess up in my drill press, aligned the gear on the shaft until a 1/8" bit slid through easily, ran a 3/16" bit SLOWLY through the gear and shaft to cut the hole bigger, then installed the new pin. Works great.
Bill

I thought about that too. It's interesting to note the Spirol pins' "Double Shear Strength Minimum" on 3/16" pins is 3150 lbs vs 1400 lbs for 1/8" pins. A few minutes with a drill and the strength more than doubles.

I found an interesting thread where someone actually tested various OEM pins, as well as high-strength pins from McMaster-Carr. The OEM pins were all well under the 1400 pounds specified for the Spirol pins, and the high-strength McMaster-Carr pin well above. The bottom line is he chose to stay with a high-strength 1/8" pin, though there are plenty of opinions supporting the use of 3/16" pins. Worth reading, especially if you want to satisfy your inner geek over a small, yet vital, engine component.

Ford 385 Series Engine Builders Forum: Distributor Gear Roll-Pin Experiment (For Nerds Only))

Not trying to be an arse, but you do understand the function of the pin correct?
its not just to hold the gear on. its a failsafe to save your motor if your oil pump fails.
when the oil pump reaches a certain amount of drag, like it seizing, the pin shears and shuts the motor down, don't make the pin too strong or a rod will be what shuts your motor down if the oil pump fails

Found Spiral Coiled Roll Pins at ZORO.com. It turned out I was out of gas. Why did I do all this?

yep.....been there.....be thankful

When shopping for the spiral coiled roll pins, for FE distributor I'd stay with the 1/8 in diameter pin. The drive gear boss is 3/4 in OD. but a little pin hanging out probably never hurt anything. So I went with 7/8 in. long, so beveled ends would be outside the drive gear boss. Zoro .com has different brands and materials. I like the 420 stainless, different double shear loads, I saw 1400 lbs. and 2000 lbs. and remember the pin should be ok but may need to break under extreme circumstances. it's a fail safe and the different brands have different quantities in a package , some are 25, 50, and 100. they have quite a list
Drilling a larger hole makes the distributor shaft thinner outside the hole. I did forget to not rev until engine oil was warmed up one time and broke the original split spring roll pin. The engine just quit. was not real hard to fix. No real damage. remember the pictures of Brent's oil pump locking up and it twisted the hex drive shaft into ornamental iron. Did you see his pictures of his engine bearings? that was a crutch engine , but.

full of doubt
 

I apparently I now have the 1100 LB. (light duty) pins (small pile). I'm now full of doubt again. Yes, I did see that slotted roll pins rated at 1875 lbs. If that was what I had fifteen years ago , I broke one of those. back to the coiled roll pins. Which material SS or carbon steel? how heavy would you go? I have a small pile of lite duty rated at 1100 lbs., standard duty looks to be 1400 lbs. and heavy duty is 2000 lbs. I'm not above ordering a small quantity to have on hand now.

I went with ZORO.com again. minimum order was 2 packages of 25 pins =50 pins
G3396018, 1/8"x 7/8" spring pin, heavy duty, coiled, material 420 Stainless Steel , 2000 LBS. double shear rating $9.37 per package =$18.74+ $5.00 shipping. So I'll have another pile of pins.
Huyett .com had minimum order of 10 pins .$2 something but had a small order fee of and more shipping$10