Distributor gear pin shears on me....any suggestions to help prevent this from happening again?

I figured since most of the experienced guys have moved to this site, I'll post this and get your opinions.




We had a problem Sat. night with the gray bird. My wife was cruising down the track after picking up her trophy and I hear this loud "POW" downtrack. It came from the Bird. Definitely a backfire in the exhaust. Then the engine dies.
The first thing I checked was that the rotor was turning, which it was.

Luckily, I was carrying a spare distributor and after I had changed distributors, the engine sounded the same and still would not fire and sounded really weird on the 2 times it tried. I played with moving the timing around but no luck.
So I decided "what the heck" and put the new distr. in 180 degrees out and the engine fired right up !


This is what happened: The distributor gear pin sheared and then the gear spun around the shaft and hooked enough on the dist. shaft to keep turning the rotor.

My question is how do I fix a distributor so the pin will not shear again? ....(BTW: The distr. was an auto-parts house rebuild and was 5 years old turning a standard oil pump.)

Alan

Sounds like fatique Alan. I've had a couple do it before. I just repinned them and ran this heck out of them. No problems so far. The one in my motorhome did it 3 times and I double pinned it..it's still running..knock on wood!!Good luck,Dan-O

I had one giving me fits and drilled to the next size up and put a bigger pin in it. If it's been 5 years, I wouldn't sweat it though and do like Dan said and just repin it and go.

Pin it with some tool steel?

ive also double-pinn my bronze gear

Drill it out to the next size pin....5/32" .

Isn't there a measurement of like (.004-.007 not sure on this ) clearence from the bottom of the gear to the top of the boss in the engine block that needs to be checked. As long as I have had mine in spec, there has never been a problem. (knock wood) This is explained in the MSD instuctions when installing a gear.

There you go............

Thanks Lem for the scanned sheet !

We've used the larger Chevy pins in them a couple times....

Also some of the rebuilds have the soft pins,so make sure and put a heavy pin in like was said.

as long as gear doesnt wear (touch) block your fine,we have tested .005 to .0075 clearance between gear and block, no problems. just make sure it clears,we have found that not all blocks are mach the same in this spot

Pull the shaft completely out of the housing and check to make sure the oil groove is cleaned out. I put a rebuilt in my truck several years ago and sheared 2 pins before I figured it out. Without any oil getting to the top bushing, it was seizing up after running for a while.

were can i get these super strong pins from and the matching drill size. ????

That should be a 1/8" pin and you should be able to get that at NAPA.

I have done the double pin and went to the bigger pin both works well. I did buy some extra shafts from MSD because I checked the dimensions per the sheet posted here and found the gear was .015 off on a new unit which would cause wear on the gear.