Distributor gear roll pin. Need some expert guidance.

Help Support 7173Mustangs.com:

turtle5353

VIP Members
Joined
May 15, 2011
Messages
3,434
Reaction score
272
Location
PA
My Car
1971 Mach 1 Mustang
Were those stock valves?  Mine were stock valves and they are notorious for the heads coming off the stems. Mine had the valve head pop off the stem and went into the cylinder and destroyed it almost exactly like yours.  My motor have very few hours/miles on it.  
 

D730C0E7-5115-486C-95E3-9EB3329D2E2F.jpeg E65676B0-E04E-44D1-A6E3-7C7E8A8EC675.jpeg EF1415D0-4F61-42E8-906F-07DB0055A25D.jpeg 2474AD59-78D8-4152-B0B6-F0DB5E11F1F0.jpeg 7580FFF3-6065-4771-8B63-F1265E337B86.jpeg A2F69A2A-F623-4C1D-A9F6-5EA9809BA10C.jpeg 3EB56FDC-2DF5-4EE1-92FD-D44C27BB1870.jpeg 78E48041-8C52-4EA3-B41E-E3022EC9D7DF.jpeg

 
Last edited by a moderator:

kcmash

VIP Members
Joined
Sep 2, 2012
Messages
1,469
Reaction score
100
Location
Blue Springs, MO
My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
Wow!  That is unbelievable.  Yes, I believe these were stock valves.  When I bought the parts with these heads they were stated to be NOS Boss Heads.  But the fact that you lost #6 exhaust also is totally uncanny!

I have never seen a failure like this on any original Clevelands, and me and my brothers have had them since the 80s.  The fact that you had the same failure in the same cylinder is just crazy!

kcmash

 

Hemikiller

Tech Advisors
Staff member
Moderator
Joined
Jul 12, 2010
Messages
3,577
Reaction score
786
Location
Killingworth, CT
My Car
71 Mach 1
65 coupe
Common problem, you take the factory Ford valves and bin them immediately. The guy who bought my old 71 dropped a valve, but he over revved it by going into the wrong gear. The block survived because it had factory cast pistons, not forged TRWs. These were also NAPA replacement multi-groove valves made by TRW.

351C-001_dead.jpg

351C-002_dead.jpg

 

kcmash

VIP Members
Joined
Sep 2, 2012
Messages
1,469
Reaction score
100
Location
Blue Springs, MO
My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
Well, I think I found the true source of the failure.  Into the confessional of stupidity I go my friends.

Today I noticed something a little off when looking at the engine and heads.  It appeared that the water jackets had quite a bit of rust in the heads.  When I looked closer I found that the drivers head gasket had been inverted, blocking the front side water flow.  This makes sense as the head likely got early hot, causing he exhaust valve to seize in the guide, this drawing the failure.

Why it did not happen sooner is beyond me!  The Machine shop feels that was the driver to my demise.  I feel really stupid because I have built enough engines to know to watch for details like that.  I must have been in a rush that day and made the error.  We will see if the head can be salvaged, or if I need to replace the one head.

kcmash

 

turtle5353

VIP Members
Joined
May 15, 2011
Messages
3,434
Reaction score
272
Location
PA
My Car
1971 Mach 1 Mustang
That sucks. But it is easy to do with our Clevelands.  I would say as long as the head isn't cracked or anything, you can replace the guide and seat and be OK.  Just be sure to replace those valves with good quality aftermarket valves. I went with Ferrea on mine. 

 

kcmash

VIP Members
Joined
Sep 2, 2012
Messages
1,469
Reaction score
100
Location
Blue Springs, MO
My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
Steel Gear for the Distributor. The gear on my distributor attracts a magnet. Should I still order a "Steel" gear for my roller cam since the cast iron gears would draw a magnet too?

kcmash
 

Hemikiller

Tech Advisors
Staff member
Moderator
Joined
Jul 12, 2010
Messages
3,577
Reaction score
786
Location
Killingworth, CT
My Car
71 Mach 1
65 coupe
Well, I think I found the true source of the failure. Into the confessional of stupidity I go my friends.

Today I noticed something a little off when looking at the engine and heads. It appeared that the water jackets had quite a bit of rust in the heads. When I looked closer I found that the drivers head gasket had been inverted, blocking the front side water flow. This makes sense as the head likely got early hot, causing he exhaust valve to seize in the guide, this drawing the failure.

Why it did not happen sooner is beyond me! The Machine shop feels that was the driver to my demise. I feel really stupid because I have built enough engines to know to watch for details like that. I must have been in a rush that day and made the error. We will see if the head can be salvaged, or if I need to replace the one head.

kcmash

The gasket is designed to force the coolant through the block, traveling to the rear, then the opening at the rear allows the coolant to enter the heads. It travels forward through the heads, back into the block to the cast-in crossover, and finally out through the thermostat housing. If your gaskets were on backwards, with the "FRONT" stamp at the rear, the engine would have overheated very quickly.


351C4Vfordad010.jpg

Steel Gear for the Distributor. The gear on my distributor attracts a magnet. Should I still order a "Steel" gear for my roller cam since the cast iron gears would draw a magnet too?

kcmash

When in doubt, replace the gear. Lots cheaper than a new camshaft.
 
Joined
Dec 14, 2017
Messages
90
Reaction score
65
Location
NW Pennsylvania
My Car
1972 Grabber Blue Mach One 351 Q code orig 4 speed. Now: 427C Titus
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
Step one: ensure distributor gear depth is correct, if it's sitting too low you'll bind the gear into the mating pad in the engine block guillotineing the roll pin. When depth is verified move to Step two: simply drill out the roll pin hole to the next larger size (remember you already verified proper gear seating depth). I generally like HV pumps, I've enjoyed excellent success with many Clevelands over many years using the above simple process.
 
Joined
Sep 12, 2015
Messages
5,797
Reaction score
891
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
Step one: ensure distributor gear depth is correct, if it's sitting too low you'll bind the gear into the mating pad in the engine block guillotineing the roll pin. When depth is verified move to Step two: simply drill out the roll pin hole to the next larger size (remember you already verified proper gear seating depth). I generally like HV pumps, I've enjoyed excellent success with many Clevelands over many years using the above simple process.
Sorry to disagree, but an HV pump caused my newly rebuilt Cleveland to destroy a cam along with the mains. The builder chose to put this in and cost him a warranty rebuild. In a stockish motor it's just not needed imo.
I do agree with you on correctly setting the gear mesh, very important. I would caution on redrilling for the roll pin. I think just 1 size larger and that's it or the shaft could be weakened too much.
 

Kilgon

VIP Members
Joined
Sep 8, 2018
Messages
1,613
Reaction score
548
Location
Ross, Ohio
My Car
71 Sportsroof Bright Red.

Steel Gear for the Distributor. The gear on my distributor attracts a magnet. Should I still order a "Steel" gear for my roller cam since the cast iron gears would draw a magnet too?

kcmash
I would look up the cam manufacturer and see what type of gear they call for on that particular cam. I would also make sure that you fit the gear to be within the specs. Make sure you use some gear break in lube.

Distributor Gear.png
 

Mico

Member
Joined
Aug 13, 2017
Messages
7
Reaction score
0
Location
Belgium
My Car
1973 T5 Mach1 351C 4V C6
For a roller cam, a steel gear distributor should be used.
I have also drill the gear and shaft to add a second pin
 

Hemikiller

Tech Advisors
Staff member
Moderator
Joined
Jul 12, 2010
Messages
3,577
Reaction score
786
Location
Killingworth, CT
My Car
71 Mach 1
65 coupe
For a roller cam, a steel gear distributor should be used.
I have also drill the gear and shaft to add a second pin

Not always, it depends upon the core used. A billet steel cam with machined-in gear needs a bronze of steel dist. gear. The cam I received a couple weeks ago from Cam Research is a billet core with a large tag on it that says to use a specific gear material. The other roller is an austempered iron core, which uses a cast iron gear, just like a regular flat tappet cam.

Regardless, when in doubt, *call* the cam manufacturer and *ask* what you need to use.
 

kcmash

VIP Members
Joined
Sep 2, 2012
Messages
1,469
Reaction score
100
Location
Blue Springs, MO
My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
OK, I go my new MSD Bronze gear today and I am at another question point.

So the MSD package say to send your Ford Distributor in to have the gear pressed on as it requires special tools.. So I am wondering if I just send the $80 gear back and change to a new or second hand Duraspark. Seems like I learn that I know less every day. I go with a roller cam, so I need a new gear, The gear needs a special install…….

I am an old school guy that used to say if it’s a Ford Distributor, stick it in there as we all had Clevelands back in High School. I have always seen people upgrading ignition with coils, HEI, and electronic. Does it really make any difference? My experience with Pertronix was not good, but I am feeling like I am wasting money with spending that much on a gear I have to go have pressed on.. The 2 distributors I have now are a Rock Auto refurbished auto lite that needs a clean hole drilled for the gear, and an generic replacement Dizzy from O’Reilly that I was running when the engine failed.

If I switch to a new duraspark kit, will it come with a gear, or will I need this gear anyway? Any help is appreciated.

Kcmash
 

Kilgon

VIP Members
Joined
Sep 8, 2018
Messages
1,613
Reaction score
548
Location
Ross, Ohio
My Car
71 Sportsroof Bright Red.

OK, I go my new MSD Bronze gear today and I am at another question point.

So the MSD package say to send your Ford Distributor in to have the gear pressed on as it requires special tools.. So I am wondering if I just send the $80 gear back and change to a new or second hand Duraspark. Seems like I learn that I know less every day. I go with a roller cam, so I need a new gear, The gear needs a special install…….

I am an old school guy that used to say if it’s a Ford Distributor, stick it in there as we all had Clevelands back in High School. I have always seen people upgrading ignition with coils, HEI, and electronic. Does it really make any difference? My experience with Pertronix was not good, but I am feeling like I am wasting money with spending that much on a gear I have to go have pressed on.. The 2 distributors I have now are a Rock Auto refurbished auto lite that needs a clean hole drilled for the gear, and an generic replacement Dizzy from O’Reilly that I was running when the engine failed.

If I switch to a new duraspark kit, will it come with a gear, or will I need this gear anyway? Any help is appreciated.

Kcmash
Just curious but why did you get a bronze gear. If the manufacturer called for it than great. If your cam will work with a steel gear than I would go with what you have.

Changing the gear is not that hard. If you have a hydraulic press just follow the you tube video below. If you do use a press be careful not to bend the shaft when pressing the gear back on.


If you do not have a press any 2 or 3 arm gear puller will work. To take the old gear off drive out the roll pin and use your puller to pull the old gear.

Several things you will want to do before pressing the new gear on. First is to draw a center line the length of the shaft along the roll pin hole center. This will help if you are going to try to reuse the hole or if you are going to drill a new hole 90 degrees of the original. Second, measure the distance of the hole either from the bottom of the shaft or the bottom of the distributor. This will come into play when pressing the new gear on. If you are drilling a new hole knowing the location of the old hole is critical. You do not want the new hole to intersect with the old or it will weaken the shaft and you will stand a chance of snapping it.

Although there are several ways to get the new gear on, the way I do them works wells. Items needed are a standard and a deep well 13mm (12 point) socket along with a couple of 5/8 " nuts and your puller. First, use some 1000 girt or better and give the distributor shaft and the inside of the bronze gear a light going over. Clean both off well. Oil up the shaft. Next determine if you are going to use the original hole or drill a new on. Start the gear on by hand as far as possible. You will now take your puller and latch the arms onto the distributor flange above the thrust collar.

Now, depending on the puller arm lengths you will use one of the two sockets to slip over the shaft and start pressing the gear. Go slow and steady. Keep an eye out so you don't bottom out the sockets. Use the nuts as spacers between the socket and gear when needed to get the gear on all the way. Once you get close use a micrometer to start checking correct depth. Use the measurements included with the gear. Once there you will need to either drill a new hole completely or drill one through the other half of the gear using the original hole as a pilot hole.

NOTE - the existing hole in the new gear may not line up height way 100% with the hole in the shaft when in specs. Seems like these are a hit and miss type things. If it does not line up and it is off just a fraction, then oblong the gear hole and finish by using the original distributor hole to drill on through the other side of the gear.

I know some will complain about the possibility of snapping the thrust collar roll pin by doing it this way but neither I nor my son have had ever had it happen.
 
Last edited:

Don C

Fords Forever
Joined
Jan 1, 2012
Messages
8,114
Reaction score
875
Location
Springfield, OR
My Car
1971 Mustang Sportroof M code
+1 on wondering about the bronze gear. They have a short life span compared to the steel gears. If you won't be driving it much should be OK, though
 
Joined
Dec 14, 2017
Messages
90
Reaction score
65
Location
NW Pennsylvania
My Car
1972 Grabber Blue Mach One 351 Q code orig 4 speed. Now: 427C Titus
All good advice from fellow members. As another option I've used distributor to block shims to FINE tune the final gear height, thus avoiding drilling the "second hole" thru the shaft. As previously mentioned, replacement gears are hit and miss with their hole height dimensions. Most macine shops or driveline shops will have shims that will work with our Fords with minor "tweaking". The shims in my arsenal are .005, .010, .015. For me a simple 1 or 2 shims is preferable to drilling another shaft hole, in addition after two shaft hole drilling the third replacement gear my have a different hole height yet again! A distributor shim takes care of this never ending variable ESPECIALLY with Bronze gears.
 

Attachments

  • 20220220_085947.jpg
    20220220_085947.jpg
    106.1 KB · Views: 2
  • 20220220_090033.jpg
    20220220_090033.jpg
    81.1 KB · Views: 2
Joined
Sep 12, 2015
Messages
5,797
Reaction score
891
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
All good advice from fellow members. As another option I've used distributor to block shims to FINE tune the final gear height, thus avoiding drilling the "second hole" thru the shaft. As previously mentioned, replacement gears are hit and miss with their hole height dimensions. Most macine shops or driveline shops will have shims that will work with our Fords with minor "tweaking". The shims in my arsenal are .005, .010, .015. For me a simple 1 or 2 shims is preferable to drilling another shaft hole, in addition after two shaft hole drilling the third replacement gear my have a different hole height yet again! A distributor shim takes care of this never ending variable ESPECIALLY with Bronze gears.
I would agree with you absolutely as the shafts are not a large enough diameter to safely allow for drilling more and more holes.
However, I might add to your excellent description on using shims that the tolerance dimensions given for the distributor, determine what thickness shims to use. One may need shims a thin as .002" to achieve those tolerances. If the gear I have will not fall within tolerance to get the holes to line up, then I'd try another gear, or with access to a mill, drill a second hole in the gear alone. Just my thoughts on what I might do if I had too.
 

kcmash

VIP Members
Joined
Sep 2, 2012
Messages
1,469
Reaction score
100
Location
Blue Springs, MO
My Car
1971 Mach 1, Grabber Blue w/Argent stripes. Original 2V 351C Auto, Tilt, rear defog, Black Comfortweave Interior. Under restoration. Original colors, 4V 351C, 4-Speed, Spoilers, Magnums, Ram Air. All Ford parts.
Thanks fort he responses.

1). I chose the Bronze gear for these reasons. 1 the tag on my Cam Research Cam was just like the one pictured by Hemikiller above. Bronze or steel. With the long lead times to camshafts now days, I figure the bronze would be an easier wear on the cam gear as opposed to steel. And the bronze was 30% cheaper so I thought that was a good move.

2) I am putting a new gear on based on advice that you should ALWAYS use a new dizzy gear with a new cam. I have a 200 mile old distributor and gear that I pulled from the old engine. I was a just afraid to use that as I am unsure if the gear is steel, and it was used with a Ford Motorsport cam, so it is not “new”

3) I see all the shim guidance and have to ask how critical that is. I say this because the Autolite Dizzy I have that was a ROck Auto refurbish has about .030 or more vertical play in the shaft . So when I tighten the dizzy down that whole gear and shaft through the middle has float, right?

I just can’t afford to smoke another engine. Trying to sort through the real concerns and the over cautious comments. Honestly this car may see 5K miles per year. Bu I want it to be reliable for that bucke list road trip.

Kcmash
 
Joined
Sep 12, 2015
Messages
5,797
Reaction score
891
Location
SW Ontario
My Car
1971 Mustang Mach 1, M code, 4 speed.
Thanks fort he responses.

3) I see all the shim guidance and have to ask how critical that is. I say this because the Autolite Dizzy I have that was a ROck Auto refurbish has about .030 or more vertical play in the shaft . So when I tighten the dizzy down that whole gear and shaft through the middle has float, right?
KC, I got curious exactly what the spec is for a 351C dist, shaft end play allowance. The Ford manual shows .024 - .035", and gear location as 4.031 - 4.038". So you're right, there is quite o lot of free play allowed, meaning the gear will tend to find its own position. None the less, I wouldn't want to be outside of those tolerances.
 
Top