Double pinning distributor gear?

If anything gets caught in the oil pump it will shear the pin (note: this is not theoretical, this has happened on numerous occaisions). Basically anything that can cause an increase in force necessary to drive the pump can cause it. No downside to double pinning. Its also recommended you get a high strength drive for the pump (goes between dist and pump).

I have personally suffered a sheared pin, which caused a WHOLE lot of pain and suffering (missed a friend's wedding and the boat that was to send the Pantera to me in France).

I'll never forget that, and have mine double-pinned.

My post is to comment that I've suffered first-hand this problem, and have read numerous times that the pin is just too weak, and there is no downside to double-pinning it.

1717 has a Unilite, and I had a shear pin failure, was just driving down the street and had a POP, then nothing. Mallory encourages driling out and using a 5/16" pin. I did this and havent had any other problems.
Jeff

The stronger pin allows somewhat larger debris to pass before the pin breaks
or the distributor driveshaft wraps up like a barber pole. One common form
of debris is from the OEM umbrella seals which disintegrate after 35+ years.
The 351C pick up has a bypass hole in the pick up screen which allows relatively
large debris to pass. The pickup from a 351M/400 truck engine does not have a
bypass hole so is more effective at blocking debris and will bolt on in place
of the 351C pick up. See:

http://www.bacomatic.org/galle...Onews17of38.jpg.html

Dan Jones

OSOFAST
Are you sure it was 5/16" and not 5/32"?

The oem oil pump drive shaft twists & absorbs shocks, but the heavy duty oil pump drive shafts don't twist so the pins shear off.

The twisting of the oem shaft causes "spark scatter", the heavy duty shaft was desinged to prevent spark scatter.

If you can put up with spark scatter, use the oem shaft and it becomes a non-issue.

Better yet, install a distributorless ignition, use the oem drive shaft, and you have neither spark scatter or sheared distrubtor gear pins.

-G

To my knowledge my oil pump drive shaft has never been modified or replaced. Does this mean I am relatively safe, or is this something I should be worried about?

quote:

Originally posted by SoonerBJJ:
To my knowledge my oil pump drive shaft has never been modified or replaced. Does this mean I am relatively safe, or is this something I should be worried about?

You're safe. Unmodified Clevelands don't have a problem in this area (the valves and rod nuts are another issue however)

I don't believe the R code/Q code oil screen has a hole in it, only the earlier - flatter oil screen. Melling #M84-AS1 oil screen (aka an oil pick-up or an oil pump suction line) is a duplicate of the R code/Q code high volume oil screen. There's a pic of this oil screen in my 351C photo album.

Or am I showing signs of senility again?

-G

I respectfully disagree on the pump driveshaft issue. Wrecking yards have lots of Ford engines (not just Clevelands) in which the stock soft steel driveshafts are twisted or broken. It's easy to spot; the driveshafts are hexagonal and the edges are often twisted in a graceful spiral. Additionally, the hex-edges that actually drive the pump are worn almost round in some engines. A round shaft will not power an oil pump for long. A characteristic of Ford V-8s is, a broken oil pump shaft does not shut the engine down.... for a few minutes. Then it seizes and you get to spend a couple of thousand $$ to overhaul it. Performance driving, high rpms, bolt-on power adders, high-pressure or high-volume oil pumps or even shimming the pump relief valve- all can overstess the pump driveshaft and drive-gear spring pin. A 4130-steel pump driveshaft from Ford Motorsports, Moroso or Milodon will cost less than $20 and IMHO is cheap insurance. They install exactly like stock.
FWIW, the coil-of-thin-steel spring-pin failure mode in distributor drive gears is, impacts from micro-debris going thru the pump progressively cracks the thin layers until the pin breaks in two. On some engines during the progressive failure period, the distributor retards perhaps 20 degrees, causing lots of heat, detonation, pinging and loss of power.
If you have trouble finding real roll pins to double up in your distributor gear, a short piece of drill rod, staked on each end also works. Again, real roll pins or a chunk of drill rod literally only costs a few pennies and is very cheap insurance. Buying a high-buck ignition distributor is no guarantee, either. They all use the same cheap spring pins and they all can fail the same as stock. Both of these breakdowns have happened so often, it ought to be a mandatory upgrade for all pushrod Fords. Tell your mechanic to just do the mods; a free tow-truck ride is not fun at any time.

Jack,

How does one identify a "real" roll pin, especially if purchasing online? Do you have a source and part number?

John

I got mine from McMaster-Carr. I can send extras if you want them. (they were a bulk item I think I got 25 or so)

quote:

I got mine from McMaster-Carr. I can send extras if you want them. (they were a bulk item I think I got 25 or so)

Thanks, but how do we identify a "real" roll pin?

John

quote:

I got mine from McMaster-Carr. I can send extras if you want them. (they were a bulk item I think I got 25 or so)

Hey Husker,

I could use one if you can spare an extra. How much would you want?

Jack,

For people who missed your article in POCA, that dealt with double pinning distributor gears, perhaps you could put the specifics in this thread, so people know exactly what to use.

I have wanted to do this mod for a number of years to my OEM dual point. However I have been warned against pulling the distributor because of potentially having the distributor gear drop in to the oil pan. Not really sure how this could happen unless the pin is already damaged.

The individual who guided you in that manner is an alarmist. The gear is pressed on and in most applicatons requires reasonable force to even rotate it on the shaft w/o a pin. I'd take that bet for big money.

A more reasonable concern is the oil pump shaft. I have heard of incidents where rebuilders have neglected application or positioning of the Timmerman Collar that prevents the shaft from separataing from the oil pump and dropping into the pan upon removal of the pump. Also, a low probability event.

Go ahead pull it.

Oops, for better accuracy, "dropping into the pan upon removal of the pump" should read "dropping into the oil pan upon the shaft's disengagement from the oil pump"

Maybe thats clearer

Garth66: I PM'd you.

I've read enough posts where owners have sheered the pin to make it worth it. Its an easy mod to prevent a failure, even if a low probability, which would leave you high and dry.
BTW when I replaced my gear it was not pressed on.