300 Inline 6 distributor roll pin sheared(1968 F500)

[dolinick]

I already posted in my 1968 F500 thread in project updates but I now know my roll pin is sheared in the distributor gear.

I have been trying to get this truck running which has been parked for 8 or 12 years. I am thinking probably 8 years because
the registration and inspection are good until 2012.

I messed around with the carb when I got it home but it never ran properly until one day I pulled the distributor and reinstalled it.
It idled smootlhy for about a minute but stalled once I tapped on the throttle. It backfired, carb caught on fire several times.

Yesterday when I pulled off the distributor cap It looked like the timing was out about 90 degrees. I dropped the bolt and retainer
for the distributor so I drove to u-pull-it and found a couple. Anyway there were several split exhaust manifolts from later EFI
straight six engines. For those of you who want true dual exhaust for your inline 6. but i digress.

When I got home I reinstalled and attempted to set the distributor close to 10 degrees befrore top dead center. I did this by rotating the
until the little notch met the first or about five little marks next to the harmonic balancer(i think that is what it's called). I actually could feel
air coming out of the cylinder as I rotated the engine. Anyway I turned the distributor until the points began to open then advanced it just
slightly. I watched a youtube video of a guy showing how to do it with a v8 electronic distributor.

When I tightened down the distibutor I went and turned the key. I hadn't messed with it since yesterday. The engine started right up and
ran for almost three seconds. I pressed the accelerator three times, held it wide open and turned the key again. This time only a flame
shot out of the carb and it would not start. I removed the distributor cap and noticed that I could freely turn the rotor.

I'm not sure if the pin just sheared or it was sheared all along. maybe the gear was stuck on there so tight that the gear stayed in place
long enough for the engine to start those other couple of times.

I was beginning to think the timing gear was bad before this happened. But the other day I noticed only a small amount of oil coming to the
top of the valves. Then I changed the oil and filter. Now could my oil pump have caused the pin to shear right now? I have an idea how to test
this. I got to turn the oil pump with the distributor removed. Anyway, should I install a new distributor, fix the old distributor or install a new oil pump and a new distributor?

I already got a new carb, coil, and fuel pump.

Here is the video of the truck starting today: https://youtu.be/VjKbiHjEkz0

[1972hiboy]

Had a roll pin shear in a 400m in a 79 f150 I had in high school. Once I figured out what it was ( which took waaay to long, but then again I was a kid ) I showed the auto shop teacher and he said if the gear and shaft look alright go ahead and put a new roll pin in it. So that's what I did, put it back in the truck and went on my merry way. never had a prob with it again.

[sargentrs]

Same here with an '85 F150, 300 inline 6. Just quit one day. Pulled the distributor cap and rotor wasn't turning. Pulled the distributor out and heard the sad sound of the gear dropping off and down to the oil pan. Got it out, new pan gasket of course, went to parts store, got a roll pin that was close, drilled the hole to fit the new roll pin. Reassemble, reinstall, set timing and drive. I have no idea why it sheared in the first place.

[dolinick]

Same here with an '85 F150, 300 inline 6. Just quit one day. Pulled the distributor cap and rotor wasn't turning. Pulled the distributor out and heard the sad sound of the gear dropping off and down to the oil pan. Got it out, new pan gasket of course, went to parts store, got a roll pin that was close, drilled the hole to fit the new roll pin. Reassemble, reinstall, set timing and drive. I have no idea why it sheared in the first place.

i might look for a roll pin later. it's gonna run so maybe i can move to the brakes...

[dolinick]

well i went to autozone and they had a package of roll pins of varous sizes for about five bucks.
i bought it and went home and stuck it in the distributor. stuck the distributor back in and tightened
it down. turned the key and the truck starts right up and idles with a slight misfire.

i drove it around the block with no brakes. i was gonna leave it in first gear but i got it up to third
on the back stretch. i live on at the bottom of a slope so it's kind of scary. the parking brake is strong
enough to keep it from rolling. needless to say i parked the truck, engagedthe parking brake, left it in
first gear and chocked three of the wheels just to be safe.

I opened the brake reservoir and it's only power that i think is rust...

[sargentrs]

she rolls! Congratulations!

[tsherry]

If it does it again, better check your oil pump gears. I had something (piece of a gasket ) get sucked into the oil pump past the screen, up into the oil pump, and the pump locked, sheared the pin. Happened twice before I figured out the problem wasn't with the pin.

(351W in my '69 Galaxie)

[dolinick]

If it does it again, better check your oil pump gears. I had something (piece of a gasket ) get sucked into the oil pump past the screen, up into the oil pump, and the pump locked, sheared the pin. Happened twice before I figured out the problem wasn't with the pin.

(351W in my '69 Galaxie)

I've been running the engine a few times since april 1st. Today I got the rpm up a little bit. Maybe the previous owner didn't
drive it very often and didn't change the oil very often. Well, I don't know what caused the pin to shear. It seems okay for now.
The only guage on the dash that seems to work is the oil pressure guage. The truck idles smooth now. It sounds ok to me so
I don't believe the engine is worn out. I was told to do a compression test however.

So why are there two vacuum connections on the distributor? Only one was connected to anything when I got the truck.

[My427stang]

So first, typically the reason for a pin to shear is that the location of the gear on the distributor is wrong, it pushes against the block and works the pin. This can happen from a cheap rebuild (very frequent) or from one that doesn't have the proper gasket underneath on some. If it's running and staying running, you are likely OK, but if you are concerned, I would find the proper depth for the distributor gear, pull it, measure it, and sleep well or correct

Second, the second port on the distributor is a retard function, one of the early tricks for emissions and building exhaust heat, usually when on the choke. That distributor will likely run best on just the outermost nipple, and leave the inner one (closest to the distributor body) not connected. Set your initial timing with the vacuum disconnected, and connect vacuum to ported vacuum after setting timing (vacuum source that is dead at idle, once choke is open, engine is warm and idling)

[dolinick]

hello, i got a timing light and tried to set the timing. however, i do not know what the marks mean. there appear to be five timing marks on the engine and on notch on the harmonic balancer.

[jzjames]

Timing marks should be, left to right; 14, 10, 6, 3, TDC.

[dolinick]

Timing marks should be, left to right; 14, 10, 6, 3, TDC.

Thank you. I got a photo of a timing cover and saw that. So I set it to 6.

[jzjames]

Ive got mine at 10. 6 may be too little.