Heya everyone,

My wife's Bronco died on her on the interstate yesterday morning and she had to have it towed. Turns out, the distributor gear sheared the pin off again. Last time was about 7 months ago.

Is this just a coincidence? Or is something possibly causing this?
Thanks

 

Does it have a flat-tappet hydraulic-lifter camshaft ? you must match the distributor drive gear to the cam. Just thinking out loud

 

It does. It's the stock camshaft for the 300.

 

On the duraspark II distributor there is a steel gear (smooth surface) and a cast iron gear (rough surface) .. I remember reading something about this being important which gear was used but at the moment I'm not certain which needed to be used with the flat-tappet hydraulic-lifter camshaft .. I would imagine if the wrong gear were used you could effectively have your problem .. Being stranded what a pain .. Is the dizzy original to the motor ?

 

Here is a good discussion on the topic

 

check the backlash on the distributor gear when installed with new pin.

check wear pattern on distributor gear.

check end play and side play on distributor shaft.

 

Last time this happened did you put in a different overhauled Dissy or just repair / replace the pin?

Jim

 

FORDSIX PERFORMANCE • View topic - Cam gear pin shears off

A poster on the FSP site is having the same problem.

 

Sorry to hear of the problem, AbandonedBronco. Harte3 just beat me to the punch... I, too, was going to post the same link.

Have you possibly just changed oil to a heavier weight for the Summer?

 

Thanks for the replies everyone.
The first one that sheared off, the distributor was from the junk yard and was in my motor for a good 20,000 miles. I was flooring it up to about 4500 RPMs from a stop when it suddenly sputtered and went dead.
I replaced it fully with a new distributor.

This time, my wife was cruising down the freeway at 65 / 2400 RPMs when it just suddenly lost power.

I'll have to get a better look at the gear when I pull it out of the engine. Right now, it's over at my brother's house since it cost less to tow it there. Right now, it's just sitting on top of the oil pump, since I didn't have a good enough tool to grab it.


It's the original pump (not high volume) and I'm running 10w30 for the summer. Nothing special.

How would one check the backlash on the gear? Not sure what that means.
I'll look the rest over and see if I notice anything odd.

 

Right now you can get a new Dissy on Ebay for $44 with shipping included.

eBay item number:
321268803194

You can even pick your color of choice for the cap. The one I bought of ebay only lasted 2000 miles of so before the pin shear. I was just cruising down the freeway at a steady speed. I don't think the gear was a "press fit" on the shaft, just hanging by the roll pin. When you get the parts in hand see if the gear just slides on the shaft.

I used a NAPA rebuilt Dissy ($45) and did a road side swap, been fine ever since. But I do have a spare Dizzy behind the seat.

Oreilly has a Cardone reman for $46.
As much as I like the new parts idea, you have to wonder where they come from and why are they so cheap.

Cardone® Remanufactured 30-2669 - Distributor | O'Reilly Auto Parts

 

I agree with that. It makes me wonder if it sheared because something is going on with my engine, or because the pin was made of cheap pot-metal.

Either way, they already have another one in for me as it's under warranty, so i just need to go get it and swap it in. I'm mostly looking to figure out how to prevent this from happening again.

 

It's a remain duraspark II, right? The most important thing is going to take deyailed pics of both the current dizzy and the new one you'll be able to compare the gears side by side to get an idea of what's up .. The sheared pin is a problem for sure but the big question is it doing damage to the can gear .. Here is a photo of what one of those cheap after market HEI dizzy's did because of the dizzy gear



"As you can plainly see, the factory cam shaft gear (RIGHT) was eaten away by the hardened steel gear of the new distributor."
It should look like the new gear to the LEFT..."

This article has some good info in it Distributor Installation Practices - Shaft Play And Depth - Circle Track Magazine

 

Something else I remembered

Topic 2: Excessive Distributor Gear Wear on Ford

Excessive distributor gear wear can be a problem with Ford engines. Most of the time, the problem is a result from the use of a high volume oil pump. High volume oil pumps put a lot of stress on the distributor and cam gears. A high volume oil pump is not necessary on a street driven engine that turns no more than 7000 rpms. Only extreme racing engines require the high volume pump. Should you use this type of oil pump, the following precautions will save your distributor gear from early destruction.


(1) Drill a .030" hole in the lifter/oil galley plug behind the distributor. This will allow additional lubrication on the distributor and cam gears. This will not lower oil pressure enough to hurt the engine.
(2) Ford oil pump mounting brackets have elongated holes. Due to this, the distributor shaft and oil pump shaft should be aligned so that the distributor turns freely before tightening the mounting bracket bolts. Failure to do this will cause a binding situation, thus damaging the gear.
(3) Stock Ford hex oil pump drive shafts are know to vary in length which could cause a bottoming or binding situation.
(4) Brass distributor gears can be used to avoid damaging the cam gear. Brass gears are softer and can wear out quicker than the cast gear, but will not cause damage to the cam gear. If using a brass gear, check it occasionally for wear.

Source : Diagnosing Distributor Gear Wear | Speedmaster

 

IIRC there was a cussin and discussin on the FSP site several years ago about using bronze gears on the dizzy and where to obtain them.

Also, if your oil pump is binding, sticking, etc., this might be causing the premature failure of the dizzy gear.