Setting Timing

[Gaz64]

Originally Posted by patrickt

Even if there was just the tiniest gap between the rotor tip and the terminals, that would be jumped easily by high voltage, but not register as connected with a VOM, I would think the rotor tip would touch at least some of the terminals as you rotate the gear. Any chance the rotor prong is not touching the iron ball?

This will not work as a test, I have never heard of anybody doing this.

EVERY distributor has a tiny airgap between the rotor tip and the spark plug terminal.

[Gaz64]

Sit the cap on the rotor button, you should feel the spring loaded contact of the carbon brush.

If the cap just sits there on it's own, there is no contact at the rotor centre contact with the carbon brush.

Sounds like a mismatched cap and rotor button.

[Bernica]

Originally Posted by Gaz64

This will not work as a test, I have never heard of anybody doing this.

EVERY distributor has a tiny airgap between the rotor tip and the spark plug terminal.

That was my thought too, but I figured it was just how PatrickT wrote the post.
You are correct. There has to be small gap for the spark to arc from the rotor tip to the individual spark plug lead. But PatrickT knows this!!

[Bernica]

Many folks carry an extra new MSD cap in their trunk just because of this kind of problem.

[Bernica]

Originally Posted by Bernica

Many folks carry an extra new MSD cap in their trunk just because of this kind of problem.

And also one reason I got rid of my entire MSD system and put the Pertronix dizzy in!!

[patrickt]

FWIW, here's a closeup of my rotor tip. I think they start out touching and he has a new rotor and cap. But I don't know....

[Gaz64]

Originally Posted by patrickt

FWIW, here's a closeup of my rotor tip. I think they start out touching and he has a new rotor and cap. But I don't know....

Patrick,

That is normal "burning" of the rotor tip as the spark arc jumps the gap, not from metal to metal contact.

[Bernica]

Originally Posted by Gaz64

Patrick,

That is normal "burning" of the rotor tip as the spark arc jumps the gap, not from metal to metal contact.

That is correct. I used to rub the tip of the rotor down with some steel wool from time to time and use emory cloth to sand the faces of the contacts in the cap to ensure a good arc.

[Large Arbor]

Yes, I am still apt to think I have a component issue and leading towards the coil. I will talk with MSD tomorrow and get some advice. Just bizarre issues to have two cylinders firing and nothing else. That kind of bothers me. I did not re-wire anything. The car has set and not moved. Not sure of what is going on, but I will get to the bottom of it.

Phil

[Gaz64]

Originally Posted by Large Arbor

Yes, I am still apt to think I have a component issue and leading towards the coil. I will talk with MSD tomorrow and get some advice. Just bizarre issues to have two cylinders firing and nothing else. That kind of bothers me. I did not re-wire anything. The car has set and not moved. Not sure of what is going on, but I will get to the bottom of it.

Phil

Hi Phil,

I have never heard of any V8 ignition system only firing on two cylinders.

Have you performed the MSD spark test, by jumping the mag pickup harness with a paperclip?

What is the quality of the spark, color and gap jumping capability?

Can you measure the pickup resistance with your meter?

Gary

[Gaz64]

MSD are known for rotor phasing issues, and the burning on yours shows that.

I would also look under the rotor button where the terminal screw is to see if the spark is going straight to ground.

[patrickt]

Originally Posted by Gaz64

This will not work as a test, I have never heard of anybody doing this.

EVERY distributor has a tiny airgap between the rotor tip and the spark plug terminal.

I don't know. I think they do actually touch, but they very well might not. But, it's certainly not definitive. I don't know why he would only get spark to two cylinders without something being wrong under the cap.

[Gaz64]

In a perfect world they would touch, but it would be noisy until the contacts wore each other out to zero clearance.

Some rotor buttons have adjustable tips for those who like to set minimum gap.

If you can get .001 across all terminals, you are doing well.

I think the OP is chasing a component fault.
Either weak coil, bad pickup, or bad module, or possibly bad wiring installation.

Myself, I would chuck all the MSD stuff out, start fresh with Mallory or Pertronix.

[Bernica]

Originally Posted by patrickt

I don't know. I think they do actually touch, but they very well might not. But, it's certainly not definitive. I don't know why he would only get spark to two cylinders without something being wrong under the cap.

No way they could be touching. Two hard parts (rotor tip and plug contact) rubbing together? They would either clearance themselves or break something.

[Gaz64]

Originally Posted by Bernica

No way they could be touching. Two hard parts (rotor tip and plug contact) rubbing together? They would either clearance themselves or break something.

That's correct.

[Bernica]

Change to a new cap AND rotor and try it. Another option is to borrow a working dizzy from someone and try that as well. Is your dizzy gear in good shape? Running out of ideas....