The distributor in my 460 (79 F250) recently had its roll pin break during normal highway driving. Had to get towed in, a tech replaced the pin and said it'll be OK for now but I should consider replacing the distributor altogether as the pin will likely break again. The setup I have has an Accel coil..not sure the history of the distributor but it has a regular vacuum advance. Any recommendations on what I should replace it with?

Also, any experience with those $80 HEI's from ebay?

 

Personally, I don't see all the hype about swapping in HEI. It's the same technology as Duraspark (Hall Effect); people just like it because it's more or less a one-wire setup. However, you sacrifice a giant distributor cap. Nothing is free.

It's a moot point anyway. The tech was wrong. If you're shearing roll pins, something is keeping the distributor from turning, which is usually down in the oil pump. It's possible some metal got lodged in the impeller and locked the pump. This is a common problem with high-volume oil pumps or overly viscous motor oil. The roll pin saves your camshaft and distributor gear in the event of oil-pump lockup. If it weren't for the roll pin, you'd have catastrophic engine failure.

 

Why does he think it will break again?
He must have seen another problem, you should ask him why he thinks this.
Like FMC400 said, that pin is supposed to shear if your cam and oil pump
don't want to play nice together.
A new distributor doesn't fix this problem.

I would think that-
1) you had an out of the ordinary weak pin, or
2) you have the above mentioned oil pump problems.

Ask that "tech" some more questions,
Murph.

 

Maybe something is siezing up in the Distributor shaft also. Just a Wag.

 

Its in the pump. It always is. If the Dizzy shaft had a problem, the shaft itself would show a sign. The roll pin is the fuse when a problem is below the drive gear.
Bad or frozen bearings or Dizzy shafts usually just tear up the housing, and dont really sheer the roll pin. This may not always be true, so dont let ne discredit the opinion stated above, but more times than not, the roll pin will sheer whn the oil pum experiences problems.

Oil analysis would support the contamination theory.

I too believe that this is more than likely the case, and that the punp should be looked at.
My last engine had a bad pump and the pump drive was compromised. This busted a few roll pins before I determined the problem.
After the pump was replaced, the engine seems to be fine, and the roll pin problem seems to be resolved.

 

thanks for the advice. I'll check out the oil pump.

 

I don't understand why anyone would take out a Duraspark distributor and replace it with a HEI large cap distributor. You already have a much better distributor that any large cap HEI will ever be. I can't count how many sb and bb Chevy rotors I have seen that are burnt through. Assuming you have the cap adaptor and the large cap on your Duraspark, If not you can easily adapt it to one, your way better off that a large cap HEI. Add a late model e-coil, a good brass tip cap, and a good set of wires and you will have more useable spark energy than a large cap HEI Is going to give you. The coil in the cap HEI was a bad idea from the start and did take many years for GM to dump it in favore of a separate coil. Now the control module 4 pin Gm is a great idea and much more reliable that the Ford one, but this is easy to change over too.

 

I have seen the dizzy shaft seize in the housing. This could cause the pin to shear, but the pump is most likely the problem. They did come out with a harder pin if you are running a high volume pump. I had a friend a few years back that raced and he said they never use the high volume pumps as they cause the oil to foam.

You can check to see if the shaft is seizing in the dizzy housing by simply removing the dizzy and spinning the shaft. If it doesn’t spin freely then it is seizing. Maybe this is why the mechanic suggested jgan getting a new distributor.

I wouldn’t even consider using anything but the Duraspark dizzy. Fmc400 is correct, the Duraspark is one of the best dizzys ever built. Even the racing distributor manufacturers, if honest, will admit that their dizzys are no better than the Duraspark.