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Distributor gear roll pin. Need some expert guidance.


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BLUF:  I sheared the dizzy gear roll pin yesterday at highway speed.  Need to know how to get her back on the road.

Details

351C 4v quench chamber , 4 speed car with 3:25 gears in the back.  Motorsport M6250-A341 cam, non roller. About 1000 miles on the engine.  Car was running great, oil pressure at the top of the gauge, temperature at the low end of normal.  Ran westbound on the interstate for about 5 miles, reached speeds of 90 mph with no problems. stopped at a shop to see if a friend was there, it idled well and had no problems getting back up onto the highway.  Cruising in traffic at about 70 MPH I suddenly lost power followed by loud explosive pops that I could feel in the floorboard.

I pushed the clutch in and saw the tach at 0 as I am losing speed in the center lane of the highway.  I try engaging the clutch to restart the engine and was greeted with more loud explosive banging.  I coasted to the shoulder of the highway and tried restarting.  It would crank but not fire.

looking under the car I found that both Turbo Mufflers on the dual exhaust were blown wide open.  Upon checking the rotor in the distributor I found the rotor could spin fairly freely, I could feel the drag of the oil pump, but it was not engaged with the cam.

Had it towed home, pulled the Dizzy and found the pin was sheared.  The gear shows no sign of damage, just a sheared pin.

how do I fix this and make it reliable?  I have a high volume oil pump which is likely the cause of the additional load on the dizzy gear according to some web research.  Of course other sources say the gear should be pressed on, which I have never seen on a Ford.  Will a higher strength roll pin solve the problem, or make me lose the oil pump drive shaft?

Note, the dizzy was a Rock Auto refurbish unit, so I got whatever gear and roll pin they put in.

kcmash 

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I can't help it, but it reminds me of a distributor I just bought, it's supposed to be new, and I got screwed. 
A first class fiddling has been done on this igniter, really strange fiddling.

And you can see the stock distributor from my 73 Mach 1 and its original pin.

Hope nothing else has been damage in your engine.

Good luck.

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Mustang, beer and rock'nroll

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Posted (edited)

Go to your auto parts store and get a new roll pin, align the holes in the gear and distributor shaft, and drive in the new pin.  Rotate your engine to have the number 1 piston at TDC.  Reinstall the distributor with the rotor at the number 1 position on the distributor cap.  Start the engine, set your timing, and you should be good to go!

Get new mufflers.

Edited by Sheriff41
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Do you by any chance have a Melling High Volume oil pump?  I ask because I broke an Accel distributor shaft in my 351C in the 70's, then went through 3 roll pins in my 460 over 10 years.  It was so bad that I started carrying a spare distributor with me. 

I read somewhere that 335 (351C, 351M, 400M) and 385 series (429,460) engines do not like the high volume oil pumps. I swapped in a stock oil pump a few years ago and have had no problem since....

 

Bob

 

Tachs, Voltmeters, Headlight kits, Wiper delays and more at

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Rocketman's Classic Cougar (and Mustang) Innovations, LLC

 

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Not only will the high volume oil pump keep breaking roll pins, it will also increase the wear rate on both the cam gear and the distributor gear. 

I haven't heard of extra strength roll pins. The only thing you might try, until you get a standard volume and pressure oil pump installed, is to install a smaller roll pin inside of the main roll pin.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I know that Cleveland’s are advertised to have oil restriction problems,  I will have to see what I put in there as the engine was purchased with all the parts and I assembled it nearly 10 years ago.

Looks like the remanufactured dizzy didn’t help me either.  The holes look really buggered up.

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6 hours ago, Sheriff41 said:

Go to your auto parts store and get a new roll pin, align the holes in the gear and distributor shaft, and drive in the new pin.  Rotate your engine to have the number 1 piston at TDC.  Reinstall the distributor with the rotor at the number 1 position on the distributor cap.  Start the engine, set your timing, and you should be good to go!

Get new mufflers.

Don't forget to make sure you're on the compression stroke.  I use a piston whistle stuffed into the #1 spark plug hole.  

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3 hours ago, kcmash said:

I know that Cleveland’s are advertised to have oil restriction problems,  I will have to see what I put in there as the engine was purchased with all the parts and I assembled it nearly 10 years ago.

Looks like the remanufactured dizzy didn’t help me either.  The holes look really buggered up.

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It appears that that distributor shaft is toast.  Those holes should be perfectly round.  With those edges, I would worry that any new pin would be more easily broken.  If it were me, I'd replace the high volume oil pump with a standard oil pump, and also check the oil and oil filter for any metal bits that might suggest a complete rebuild is needed.  If the oil comes out clean, with a new pump and new distributor shaft (or distributor) you should be good.  Of course, that is just me, and I'm probably over cautious.  I hope there's nothing else wrong in that mill that a new dizzy can't fix.   Good luck.

 

Ron

The Rickster, a 1973 Mach 1, being restored as a tribute to my brother who passed away with COVID in July 2020.

Billy, a 1976 Ford Bronco, also needs a lot of work.

El Guapo, a 1986 F150, frame-off Resto-Mod.

Also, in the queue, a 1950 Ford F1 Panel truck and 1962 Falcon Ranchero

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Where does the roll pin end up when it sheers off?  If my math is correct, both ends of it have to snap off for the gear to spin freely on the shaft.  There would be at least 2 parts of metal falling down and hitting the distributor gear, possibly the cam gear, and then do they make it down into your oil pan?  Those parts of metal by themselves may be small enough to get sucked into an oil pump.  And they may get chewed up on their way down there and become even smaller and break into more than 2 pieces.

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Well, my fears are being realized.  
 

If I am unsure of the oil pump is there any way to tell without pulling the pan?  I remember you are supposed to be able to pull a pan with the engine in the car.  Has anyone done that lately.
 

So the good news is that when the pin sheared the engine was dead and the pump was not pumping, so no metal should have been sucked into the pump.  I can pull the engine, but I really don’t want to.  If there were  a way to verify high volume versus low volume I may not need to pull the pan at all, just change the oil

I appreciate the help.

kcmash

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So let’s go a little deeper before I have to pull the friggin engine.

 I have been running the 20w 50 high sink Valvoline Vr1 oil since new.  My oil pressure has been at the top of the range ever since I got it on the road.

Yesterday when making my highway run, I had it up to 90 mph and possibly 3500 rpm.  I went to normal residential speed and stop lights with normal temp and oil pressure.  When making my return run on the highway I was closer to 70 mph when it failed.  
 

Do we think the problem is the way the holes are drilled in the dizzy shaft, or are the holes in the dizzy shaft the result of the failure?  Also, do all dizzy gears have 2 sets of cross drilled holes, or should they only have 1?

kcmash

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Are the 2 missing ends of the roll pin perhaps still stuck in their holes in the gear?  Maybe you got lucky and the pin snapped, but the distributor gear held onto the ends so they didn't go flying.

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You can take the oil pan out without removing the engine. I did it not long ago. However, you need to lift the engine a couple inches. I did it by jacking on the oil pan bolts with a piece of wood. After lifting the engine use a 2x4 between engine and mount. You can also lower the sway bar for more room. Get the oil pan down and replace the pump. It is tricky to get the oil pan up and making sure it seals.

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1971 M-Code Mach 1 w/Ram Air, 408 stroker, 285/291 0.558" roller cam, Blue Thunder intake, TKO600, Hooker headers with electric cut-offs, FiTech EFI w/ RobBMC PowerSurge pump

Strange center section with Truetrac, 3.5 gear and 31 spline axles, 4-wheel disc brakes

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If the ends of the old roll pin are stuck in the gear, you're all set. Replace the pin and carry on. 

I'd consider switching to 10W30 VR1 with the high volume pump. HV pumps should only be used with appropriate racing bearing clearances, not stock. With the thick oil, HV pump and tight stock clearances, you're putting a lot of stress on the system. 

Double pinning the gear is an option, but it's treating a symptom, not the cause. Running it as is with a double pinned gear, it'll find the next weak link which will be much more expensive than a $.10 pin. 

Best solution is to drop the pan and replace the HV with a standard volume pump, but it's not needed if you run thinner oil. The only 351C I sheared a pin on was a tired 4V engine that I put an HV pump in because I had it and was running 20W50,. It broke one very cold winter morning before leaving the driveway. 

 

 

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The hole in the distributor shaft wasn't lined up properly so they created an oblong hole allowing the gear to rotate slightly under load. This stresses the pin and will cause it to fail again. I'd get another distributor. An option is to have a COMPETENT machine shop locate the gear on the shaft properly (see Ford manual) and drill a new hole in the gear and shaft. Factory Ford distributors have the gear pressed on, many of the aftermarket one just slide on, placing more stress on the pin. All the MSD distributor I've bought have the gear pressed on. I hope you get it going again without too much drama. Chuck

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So here are my problems.

1) Neither O Reilly or Napa have the roll pins.  They have some generic cad plated stuff but nothing strong.

2) The gear I have has 2 sets of cross drilled holes that look different sizes and it slips on.

3). I have been running the 20w 50 because that was the only weight they had on the shelf in high zinc.

The good news,  I have a spare dizzy shaft with a clean bore in it.

So I am wondering this.  With the poorly drilled holes and poorly fitting gear( non press fit) from Rock Auto combined with the 20w 50 enough to be the lethal combination.  I am unsure if my pump is high volume or not.  In other words should I do the following.

A) Rebuild the dizzy with a new shaft , gear and double wall roll pin.

B) Switch to a 10w 40 and use a zinc additive.

C) Test drive to see if that puts my oil pressure back down to the middle of the gauge range.

 

 

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The typical repair to any type of gear, sleeve or what have you, is to re-drill @ 90 deg. After that, a shaft of this size cannot be drilled again, it's scrap. Re-drilling is not something one can easily do at home unless you have a mill and machinist tools to set up, center drill and final drill the correct size for the roll pin. Roll pins can be bought at any bearing supply store or I have seen them at good hardware stores. Don't buy the nice shiny ones!

In your case, you'll at least need a new shaft and you'll need to check the bushing in the housing as well for correct shaft fit. Basically, you're into a distributor rebuild. If you're running a stock Autolite/Motorcraft dist. why not upgrade to a properly curved DuraSpark.

As for the oil pump, a high volume pump caused my rebuilt motor to have to be re-rebuilt. It caused the first lobes on the cam and the lifter to wear out prematurely and also took out the main bearings. Unless the build is done expressly for a H/V oil pump, don't use one. If you have any doubt, change it to a know standard oil pump which may need to be set up correctly. I only use 10W30 oil with ZDDP additive.

Geoff.

 I learn something new every day!

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Thought about the duraspark.  What do you mean by properly curved?

if I head to pic n pull and yank a dizzy from an 80 s or 90s F150 with a v8 will that work.

otherwise I have my original dizzy from the original car with over 120k miles on it sitting in the garage.

Sounds like everyone is saying go straight for an oil pump change.

kcmash

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31 minutes ago, kcmash said:

Thought about the duraspark.  What do you mean by properly curved?

if I head to pic n pull and yank a dizzy from an 80 s or 90s F150 with a v8 will that work.

otherwise I have my original dizzy from the original car with over 120k miles on it sitting in the garage.

Sounds like everyone is saying go straight for an oil pump change.

kcmash

No idea about the pick and pull part if it will be close for OUR engines. As you know Cleveland's are a different beast. It likely could be reset to run at around 14 degs. initial and 20 degs. on the crank side for a total of 34 degs. mechanical advance, but I'm not familiar with DuraSparks to offer any help. There is a company, name escapes me, that will build a DuraSpark to your engine specs, not cheap, but may be worth it.

For me, the problem with using an old dist. is it was set to run at about 6 degs. initial and 30 degs crank. BUT in a pinch it might get you by for a while. Or you could carefully strip it down for parts to rebuilt the one you have, but even then, I doubt the curve will be anywhere near what we need. That was my experience. There has been much posted on the subject of re-curving a Ford distributor.

Geoff.

 I learn something new every day!

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Well I am looking at options.

Distributor.  Should I buy from a local parts house, a new one from CJ or NPD, or see if Ford will sell one.  Are the ones from the Mustang vendors good enough for street use?

Oil pump,  CJ has Sealed Power brand, while OReilly has Melling.   With all the restored crap on the car looking so clean, I am going to go in from the bottom.  I also sold my engine stand and hoist a few years ago, so I don’t have those tools.

kcmash

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I'd look at Oreilly's under the Spectra Prime name (still made by Rich Porter Technology I think). It is a completely new distributor and includes cap and rotor. The curve won't be exactly what you want but can be recurved. A lot better part than anything from Cardone, A.K.A. "Car Done". Chuck

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Valvoline VR-1 oil is also made in 10-30 and 10-40. You will need to special order it at most chain auto parts stores. My local speed shop has all the mentioned grades on the shelf.

Thanks, Jay

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I had this happen to me using a high-volume pump. Last time I used a high-volume pump.

I would get hold of Scotty at Parkland Performance Auto and have him set you up with a new distributor. He will set up  the advance curve for your engine combination. He could probably also double-pin the drive gear for you but you would have to confirm as I am just guessing on that one:

http://reincarnation-automotive.com/

Matt

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31 minutes ago, mjlan said:

I had this happen to me using a high-volume pump. Last time I used a high-volume pump.

I would get hold of Scotty at Parkland Performance Auto and have him set you up with a new distributor. He will set up  the advance curve for your engine combination. He could probably also double-pin the drive gear for you but you would have to confirm as I am just guessing on that one:

http://reincarnation-automotive.com/

That's an interesting link Matt, Looks like someone to keep in mind for the future.

Geoff.

 I learn something new every day!

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Before strengthening the roll pin please keep in mind that this is designed to break if the oil pump gets stuck, to avoid further disaster to your engine when it runs out of lubrication. 

Just my 2 ct.

Cheers Frank 

1972 Mach 1, 351C-2V, wimbledon white, blue all vinyl luxury

born in Dearborn, grown in the district of San José, spent a lifetime in California, moved to Germany in 2010

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