My car felt off a little and I couldn't figure out what my issue was untill the car crapped out on me last weekend.My daughter came and gave me a jump that didn't work so she gave me ride back to my garage to get flatbed.
Had strong spark to the cap and next to nothing to the plugs....the MSD rotor burnt through the rotor and the spark was going to the disributor shaft.I was a "a" man 20 years ago but never have seen this!

I’ve seen that twice in my life. Once on a bone stock dodge ram pickup, and once on a supercharged camaro. The ram truck had a set of plugs and wires installed by a customer. He said the truck never ran quite right AFTER he “tuned it up” said it ran for a month, then wouldn’t start anymore. He told me it had spark and fuel, so it must be something mechanical.
Going off of his info, I put a timing light on it to see if I could get a blip of timing to see if it had maybe jumped. No trigger to the timing light.... pull the plug wite at the head, no spark. Pull the plug wire at the cap, spark!
Ended up putting all factory secondary ignition parts on it and told him to leave it alone.

The camaro guy had an MSD 7 box. He tried a set of some super vood doo magic spark plugs that had some sort of halo style “strap” that was not adjustable for air gap. He burned of the “strap” of every single plug. He put in normal plugs, gapped correctly. The car still wouldn’t run. Tows it to me, figuring the engine got damaged from the straps. He tells me,”It has fuel and spark. It has to be mechanical! Something in my mind took me back a few years to the ram pickup. Pulled the cap, and saw exactly what your picture showed.
Bottom line.... check all your secondary ignition components if you are burning through rotors.
Also need to be sure of rotor phasing at peak tq rpm.

I used to see that sometimes on GM HEI ign when I worked for an independent garage. With the MSD ign it don't surprise me to see it if the rotor is old as that's something I would check a good bit if I ran MSD. I might even just replace the ign rotor yearly with MSD just to be safe. Glad you got your problem fixed. Ron

Get the Rotor Phasing dead on and the rotor tip to cap terminal radial distance as close as possible. No air gap=no spark to jump/no spark=no burn. Not possible due to the nature of the beast but make it as minimal as possible (more critical with a high energy system/multiple (MSD) sparks).

I worked at a GM dealer in the late 70's HEI had this happen all the time, they changed the plastic in the rotors and it fixed it. You need to understand electricity goes the path of least resistance, if the resistance of the plug wires, plugs, or rotor index is off, its easier for the electricity to burn through the rotor. Excessive resisatance is also hard on ignition coils as well. If you have someone who can put an ignition scope on your car, that knows how to read it, and see where the KV is would bve a big help in determining where your problem is.

This...



My Pro-billet MSD dizzy's phasing is so far off, I had to use the MSD adjustable rotor, and use almost the entire range of motion to get my rotor positioned correctly.

I discovered the problem when the metal tip of the standard MSD rotor melted and flew out of the end of the rotor. The heat that the large gap was causing a large spark jump inside the cap was intense. I was using a very high output coil too.

Once the phasing was corrected using the adjustable rotor, the rotors lasted much longer. I still saw signs of heat build up after a few thousand miles, so I swapped in a standard MSD canister coil and the discoloration from the heat pretty much went away.

Back in the late 70's when I worked at a tune up shop, we where trained to look at the bottom of all the rotors to see signs spark leakage on the bottom of the rotors. GM HEI distributors had a lot more power to transfer through the rotor that a standard points and condenser set-up, so the rotors on the HEI units would show voltage leakage in a year or two. Once the voltage made it past the rotors, it would cause the internal advance mechanism's to appear rusty with a rusty powder residue all over the internals. The mechanical advance would fail shortly afterwards requiring a replacement distributor.

Drill a hole in the cap so you can see if the rotor is pointing at #1. Then use your timing light to see where it is pointed at full advance. If it isn't pointed right at #1 at full advance then you need to adjust the phasing. If the phasing is correct then you have a different issue.

I've been running MSD distributors for years and as long as the rotor is properly phased I've never seen any issues with rotor or cap life. If the phasing isn't correct then you can have weird problems.

Is that a new MSD? They are made in china now.

Pretty common, especially on GM HEI rotors. Would happen right at the bend in the spring steel and burn out the other side. If you catch it early, it looks like a laser pin hole burn. Rotor phasing could be a contributing factor. Also the distance of the rotor tip to the cap terminals.

I have an MSD. Ignition system, 7AL2 box and Blaster coil but have never had good luck with the MSD billet distributor as I have had two of them in my Dart over the years and always seemed to have a problem with them over time. I went back to a Stock style distributor and haven't had a problem since.

Seen it numerous times over the years. HEI with the wide plug gaps, Japanese, all kinds of cars. Use caps and rotors with brass conductors rather than aluminum. Getting harder to find now though. I just consider ignition parts - wires, cap and rotor, plugs - to be consumables and replace them regularly now rather than wait until they cause problems.

With a 6 or 7 programmable,can I phase the rotor to match the spark discharge then compensate by changing the programmed timing and still be where I need to be? I also have a programmable boost retard.......

You need to phase the rotor at peak tq rpm. This needs to include any boost reference retarding.
Peak tq rpm is where your engine’s max cylinder fill/ maximum cylinder pressure events occur.
Peak cylinder pressure is where the ignition works at its hardest to fire through the mixture/ pressure. Set your rotor phase where this happens, not max advance. Advance may still need to happen after peak tq, but cylinder pressure will also be dropping, and mixture should be dropping. Both of these conditions allow phasing to be less than optimum beyond peak tq/ peak load( boost).

Im with Ron on seeing it.Saw a lot of them and the GM big HEI caps and rotors.When they came in as no starts that was the first thing we looked at.Saw maybe 2 Mopars.My MSD cap has been on close to 20 years and no problems.Think Ive changed it once.I do clean the contact though.I did have a MSD coil burn thru the side where the coil lead goes.That was close to 20 years old also.Rocky

Is Standard Ignition still around? I remember that they used to make their Blue Streak components. Caps had copper terminals. I think Neihoff did the same thing. Both American made at the time. Probably out of business.

Before I was able to get the MSD rotor,I hit all the local parts houses.The cap is the same as the GM rotor from the late 60's with points.The NAPA store came out with one to look at and it was BLUE.....
The only compant that made those were blue streak but it was the wrong one.I found a few others but they were 1/2 the weight of the MSD,chinese JUNK! I just waited for the MSD.
I also know why the car was off last time at the track.Here is the RPM graph isolated.This was with 10 lbs of boost.It fattens itself up as the boost goes up.If I made another pass I would have leaned it out 3.

Uuummm....... the engine is going 27% faster than the driveshaft?
Where in the run was that happening?

Not the finish line I hope.

On acceleration, when would the engine not be going faster than the driveshaft?

it’s converter slip........ I get that.

If it’s after a gear change, great......... if it’s at the finish line....... 27% converter slip at that point on the track....... seems like there’s room for improvement.

I installed the red version of the ignition coil that you are using and proceeded to wipe out around 4 or 5 brand new Accel distributor caps until I got the problem under control.

What I found was that this coil had so much energy that too much energy was being dropped in the cap burning out the electrodes (destroyed a cap in 3 to 4 runs). Ultimately I found that I needed to close up my spark plug gap so that less energy was dropped in the cap electrode. I ended up going from 0.042 to 0.030 inch spark plug gap. That fixed the problem.

In my case I never should have gone to the big coil - my old more moderate coil was adequate. This one puts too much unnecessary stress on the ignition components when I don't need all of that energy. With your blower I believe you need more spark energy than I do.