2stroke1971

'85 FB, 12a.....

I was poking around there this afternoon and I figured I would pull the distributor cap off...The previous owner had put a new one one 2 years back....My son drove it for a year and Ive had it for this past year, driving VERY little...\Point is, the cap cant have but about 6,000 miles on it.

Two of the contacts are beat..I mean BENT. The one marked T1, and T. (T2 is ok, as are L1 and L2.)

Im sure both of them are not making contact. Ive read that the trailing system doesnt affect how it runs all that much, but this cant be good.

The rotor has a touch of carbon on one corner of the edges, but certainly not bad looking, no crash damage....
What the heck could have done this? Im wondering if the cap was not seated right at some point in it's past....

LongDuck

'Making contact' has me wondering - you do realize that the Distributor Cap & Rotor works off of Hall effect, and no physical contact is ever made between any of the leads, correct?

Typically, when you remove the Distributor Cap, it's normal to see some arc burning across the face of the metal contacts on the inside, along with some carbon dust on the rotor assembly. These are only designed to pass closely to one another, and the stored charge in the coil is enough to arc across the air between them to pass the charge to the appropriate spark plug. Problems arise typically when someone pulls a car out from winter storage and it won't start or run correctly - as there's a hairline crack in the Distributor Cap which is causing the problem. Simple cap replacement fixes the issue. and it's caused by expansion/contraction during heating/cooling cycles of a sub-freezing garage.

More importantly, how is the car running?

If it's running just fine - there's nothing wrong with the Cap & Rotor. Put it back on and be sure it's clamped down correctly and you'll be good for many more miles. It wouldn't run at all if you didn't get at least trailing spark, and even then it would be running so poorly that you'd notice it being down on power and bad on gas mileage. HTH,

2stroke1971

Yeah man. I know how it works. point is, there was contact. two of the prongs are knocked over and sideways.
It has a stumble off idle......

[IMG][/IMG]

Hard to see them in this, I will get a better angle later....see the one at 3 o clock....it is pointed down in the picture....

j9fd3s

iTrader: (3)

i'd bet the cap wasn't on straight, its possible

NCross

iTrader: (18)

Id ebay a new one. Theyre cheap so why not?

plentymoon

I just had that happen to me I can honestly say its user installation issue and it only happened after I put the water housing and everything else back on and re-attached all my ignition it happens I just bent them back straight as I could without them hitting the arms on the distributor put it back on called it a day fired right up and still runs just as smooth and just as fast.

Just don't be aggressive with them they aren't hard to move.

DivinDriver

iTrader: (15)

Try to get one with brass contacts if you can, instead of aluminum. Better conduction, longer life, less oxidation from the arc.

Agree; most common cause of bent contacts is the cap not being properly straight.

2stroke1971

Thanks all, gonna get a new cap for sure. It will be interesting to see if it improves matters with the idle, and just off idle.

tommyeflight89

iTrader: (4)

If it makes you feel better, grab the rotor and check for side to side play. You would need quite a bit to have the rotor make contact!

As others said, most likely was on crooked at one point in its life.

Jeff20B

iTrader: (13)

Um, well I know the magnetic pickups are inductive, not Hall effect. As for the cap and rotor, that's not Hall effect either.

One quick and easy way to tell whether it's Hall effect or inductive is how many wires does it have?

Hall effect 3 wires
inductive 2 wires

2stroke1971

Well, I put a new cap on it, and it it did not solve my off idle issue but I think it pulls harder in the midrange......

In my frustration at the off idle problem , I began to remove the rat's nest. Not the whole emissions sytem mind you, just the stuff on the drivers side, all the valves, etc....
Ran the vac advance to tee and to the second port, capped the rest off.....

As soon as it warmed up, the idle dropped so low it would not run, so I set it back up a bit and took it for a drive. At first it seemed the miss was still there, but after one trip around the block and sitting in my parking spot a few minutes with it running it seemed to go away so I took it back out and it seemed pretty smooth. I did not go through setting the idle properly, to the lowest possible, etc....but ran out of time tonight.

I think I still hear a hiss under there, need to check it out some more when I get the time. Now to get the steering box adjusted, a window regulator, a stereo, a temp gauge, and maybe, just maybe, then I can drive it somewhat regularly.

NCross

iTrader: (18)

A hiss indicates a vacuum leak which would cause an off idle bog.