Why are my distributor cap terminals burnt?

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Righty Tighty

Righty Tighty

Blame it on the dog
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I popped the cap off my distributor this morning to install the FBO limiter plate, and upon inspection, found the terminals to have a "burnt" appearance. The distributor is a new Summit Racing electronic distributor, running an MSD Blaster 2 coil, blue ECU. About 100 miles on all. Engine is a mild 440 set at 22 initial (plan on adjusting the timing).

Am I running the wrong coil?

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Should be good on the gap how many miles on the cap and button?
 
the coil you have should work fine.
my opinion is something is making the ignition work harder than it should. Have you eliminated the ballast resistor? if the coil is a 12 volt rated coil you don’t need it. Also check voltage at the coil + terminal with the key on. And are all your engine grounds good as in low resistance from block to heads.
Oh I about forgot also make sure the spring contact on your rotor button is making contact with the center electrode on the cap.
 
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I don’t know if this is related to your cap problem, but That coil has a 0.7 ohm primary according to what I found on the internet. You definitely need a ballast resistor with it if you are using Mopar electronic ignition.
 
I'm not too sure there IS a problem. The hotter the ignition system, the more power is going through those contacts. It may have to do with current weather (humidity or lack of)

What are you running for plug wires? Those may have an effect. I believe MSD? does not recommend solid core wires.

If the coil is recommended as useable for the system you are using, I'd say "run it and see"
 
I am running a ballast, and I’ll check voltage once it’s back together.

@67Dart273 I just wasn’t sure the marks were normal, especially after so few miles.

One thing I did learn was that I don’t think the FBO plate will work with my distributor. Of course I learned this AFTER tearing it apart.

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Those posts are too narrow for the slots of the plate, and they’re stationary, so they wouldn’t move in the slots of the plate even if it did fit.
 
Righty Tighty said:
I am running a ballast, and I’ll check voltage once it’s back together.

@67Dart273 I just wasn’t sure the marks were normal, especially after so few miles.

One thing I did learn was that I don’t think the FBO plate will work with my distributor. Of course I learned this AFTER tearing it apart.

View attachment 1715853947

Those posts are too narrow for the slots of the plate, and they’re stationary, so they wouldn’t move in the slots of the plate even if it did fit.
Click to expand...

Yea looks normal for about 10,000 miles or so:lol:
But if it’s not misfiring just run it.
 
It runs great, up until 3400 RPM or so. With 22* initial, I’m at about 44-46 total at 3400. So I think I have too much timing and it’s detonating.

The plan was to install the limiting plate to keep me around 36-38, but this damn distributor won’t work. I’ve got the distributor back together now, so I’m going to dial back the initial to see if that helps.
 
Get a copper Echline cap and brass tip rotor. Put that cap on something with a factory coil. That rotor looks normal to me since it looks to be aluminum electrodes in the picture.
 
Sounds (and looks) like you have a phasing problem. As rpm increases and timing advances the rotor moves further and further away from the pin on the cap it’s supposed to fire to. Until it jumps to the next pin. Which is why the terminals are burning, the gap is too large and why it runs like ****. With 22 degrees of mechanical, set your initial at 14 and lock it down. That’ll be 36 total. Then work on phasing.
 
I dialed back the initial to 14, and the car sounds and drives SO much better. I can’t remember why I set it to 22 in the first place. It still doesn’t like higher RPM, but that’s an issue I’ve been chasing for a while now.
 
Moisture and aluminum terminals. I know Az you live in. Wash the engine in a year? Mopar a long time ago said to put dielectic on the rotor tip, thats right folks lube te tip
Righty Tighty said:
I am running a ballast, and I’ll check voltage once it’s back together.

@67Dart273 I just wasn’t sure the marks were normal, especially after so few miles.

One thing I did learn was that I don’t think the FBO plate will work with my distributor. Of course I learned this AFTER tearing it apart.

The pahsing is just about perfect looking at the arc on the terminals. Not getting into a pissing match on that one.

View attachment 1715853947

Those posts are too narrow for the slots of the plate, and they’re stationary, so they wouldn’t move in the slots of the plate even if it did fit.
Click to expand...
You have the Malloty style and well sought after distributor. The hex screws can be loosened and then adjust the mechanical adnvance. The tabs are there for mechanical advance adjstment. Buy a set of keys. Hope it helps.
Hoppy
 
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Righty Tighty said:
I dialed back the initial to 14, and the car sounds and drives SO much better. I can’t remember why I set it to 22 in the first place. It still doesn’t like higher RPM, but that’s an issue I’ve been chasing for a while now.
Click to expand...
Adjust the curve. Springs and the directions are available.
 
Okay, now that you mention moisture…..

My car was without a hood for several days, and it rained almost all of those days. I had the engine covered for most of those days except ONE. The engine got a little bit of moisture. I didn’t drive it that day and let it get nice and dry before starting it, but I wouldn’t doubt that some moisture got under that cap…
 
TT5.9mag said:
Sounds (and looks) like you have a phasing problem. As rpm increases and timing advances the rotor moves further and further away from the pin on the cap it’s supposed to fire to. Until it jumps to the next pin. Which is why the terminals are burning, the gap is too large and why it runs like ****. With 22 degrees of mechanical, set your initial at 14 and lock it down. That’ll be 36 total. Then work on phasing.
Click to expand...
I agree that phasing CAN be a problem but don't see it here......looks to me like the "most" of the arc is right in the middle area of the contacts.

Also just for clarity, it is not mechanical advance which causes phasing problems, but vacuum advance. The rotor and the trigger device are locked together
 
Righty Tighty said:
It runs great, up until 3400 RPM or so. With 22* initial, I’m at about 44-46 total at 3400. So I think I have too much timing and it’s detonating.

The plan was to install the limiting plate to keep me around 36-38, but this damn distributor won’t work. I’ve got the distributor back together now, so I’m going to dial back the initial to see if that helps.
Click to expand...
Way too much timing. Start at 34 total.
 
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