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When the carbon burns down like that it usually means too much voltage is going to the coil. Adding a ballast resistor solves this. Are you using a stock coil or performance coil? If you’re running a stock coil you will need to add a ballast resistor. If it is a performance coil, they do not usually use ballast resistors (unless the mfr recommends it), but you need to make sure it is compatible with the distributor.
Did a little digging around and the Distributor and coil I’m using do not require a ballast resistor, here is what I found….
“Note- Some older vehicles are equipped with a ballast
resistor or a resistance wire. These cannot be used with
this distributor. Bypass or eliminate the ballast resistor if
your vehicle is equipped with one. To check for a resistance
wire, use a voltmeter to verify that when the engine is
running that the COIL POSITIVE TERMINAL reads within 1 volt
of the battery voltage. If the voltage difference is more than
1 volt, the wire needs to be replaced. When bypassing a
ballast resistor or eliminating a resistance wire, use at least
a 14 gauge automotive grade copper wire from the COIL
POSITIVE ( + ) to the starter solenoid or a switch terminal in
the fuse box”Another thing to check would be the gap between the center of the rotor and the carbon button. If there is an air gap there the spark jumping across the gap will burn off the button. There should be no gap. Always bend the tab on the center contact up (gently) so that there is spring force to hold the tab against the button. Aside from that, poor grounding is another cause. You may need to improve or expand the grounding scheme.
I know there is no spring. The ‘spring force’ I was referring to was the act of bending the rotor’s center contact tab upwards such that when pressed against the carbon button deflection is caused.
I think you’re right, upon some more digging around I found out that you’re supposed to bend the tab slightly to make a firm contact with the button to tab….
Thanks, I’l try it with the new cap…
I don’t think your issue requires ‘checking’ the grounds. When I mentioned grounds before, I was speaking more to insufficient ground. Most performance and hot rodding manuals recommend increasing the wire gauge of main and engine grounds, and adding additional grounding wires to the head(s). While beefing up your grounding scheme cannot hurt, I have the feeling your cap issue lies with the rotor contact and carbon button as previously discussed.
First of all you need to make sure that the coil wire terminal is making good contact with the wire core inside the wire. A bad plug or plug wire will also cause high resistance and can cause the problem you’re having as well as too much gap between the rotor contact and the carbon tip in the cap. I believe that the coil wire is not making good contact in the coil tower and is arcing in there.
[quote=”wysetech” post=137599]First of all you need to make sure that the coil wire terminal is making good contact with the wire core inside the wire. A bad plug or plug wire will also cause high resistance and can cause the problem you’re having as well as too much gap between the rotor contact and the carbon tip in the cap. I believe that the coil wire is not making good contact in the coil tower and is arcing in there.[/quote]
It’s a fairly new coil wire, also, would dialectic grease help the problem?
I agree with wysetech on his thought on the wire may not making good contact with the tower. my guess is that maybe it didn’t snap all the down when you installed it, dielectric grease would help but only put the grease on the plastic part of the tower. it might let it slip all the way down instead of the rubber grabbing on the plastic and preventing it from sticking
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