[czar97]

Car idles great then after 10 minutes of driving, the engine starts sputtering, surging, stalling, backfiring etc. Got 6 miles down the road popped the hood and couldn’t keep my finger on the coil for more than 2 seconds it was so hot. Maybe this is normal.
So when I limped it into the driveway, I got a running voltage reading on the positive side of the stock coil (just before it stalled). 9.43 volts. I believe there’s something stamped on the coil about max of 6 volts. So is this 9.43 volts too high?

[Dave M]

Maybe I'm wrong but, I would think you'd want 12 volts to the coil?


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[Dragncar]

You are using the resistor wire. Full 12V needed.

[krisr]

Yeah if it's the resistor wire, use that as the trigger wire to a relay and switch +12v to the distributor.

[czar97]

I attached 3 pictures.

Question 1: Why does my coil say "12V EXTERNAL RESISTOR REQUIRED" ? Is that for the sake of saving points (which I no-longer have) or for the sake of saving this coil that I'm running?

Question 2: Can too LITTLE voltage to the coil cause the coil to get hot?

Question 3: I think I know what you're saying "krisr" regarding the trigger wire to a relay that ups the voltage from 9.43 volts (regardless we'll call it sub-12V) to a constant 12 volts.

Plan: I have a wire (switched from a rocker switch in the cab) that I actually used to switch ON a constant 12V to the coil (oddly enough) back when the wire that comes from the starter was broken (this is the factory wire that provides constant 12V during engine cranking). Currently that wire is capped protected and attached to the fire wall. I will reattach this wire to the + side of the coil (maybe right along side the rest of the wires on the + side) and switch it ON as soon as the engine starts running poorly (sputtering, surging, stalling, backfiring etc.).

Thanks again.

[SA74SD]

It sounds like your coil is "bad". A failing coil will overheat and the output drops off a lot. I would get another coil. Your coil was engineered to use an external resister to work properly. Some are engineered to use 12v full time.

[george kujanski]

What are all the wires on the coil?

You should use the coil recommended by MSD....their diagram shows a full 12V connection to the coil + and then to the distributor.

If you still have the original harness with resistor wire, that's wrong; it can't hurt to follow the instructions.

george

[chiphead]

The probillet dizzy uses an external ignition box. Are you using a MSD 6A or similar CD ignition box?

The stock points coil used a resistor wire or ballast resistor to limit the current through the coil, to prevent overheating the coil or points. This is the stock inductive ignition, where you have to saturate the coil primary with current before points open and cause inductive collapse that produces a spark in the secondary.

A MSD or similar capacitive discharge ignition charges a capacitor through the coil primary, and then dumps the current through the coil when a transistor discharges the cap across the coil primary . The natural inductive ringback causes the "multiple sparks" that MSD advertises.

The coil resistance and winding inductance of a cap discharge coil is different than a stock points coil. Get the right coil, and wire it correctly per ignition box instructions.

[Scott65]

His is a ready to run. It will work with or without a box.

[chiphead]

Ah thanks, didn't check PN. I saw "pro billet" and assumed it was the magnetic trigger model.

The RTR is a stand alone distributor that doesn't require a box. It does require a coil that is compatible with full 12V, or has an internal resistor. Typically the MSD Blaster 2 is used with this distributor.

Installation instructions with wiring linked below. Refer to Figure 10 when wiring without an ignition box. In a Pontiac, some models require using the "start" wire from the starter's R terminal to provide ignition power when cranking.

https://static.summitracing.com/glob...8_frm30253.pdf

[Richie Hoffman]

Need full 12 volts no resistor wire need d

[czar97]

Update: Added a constant 12volt feed wire to the positive and started engine. Wasn’t running a full 12 as shown on the screen of my volt meter. Confirmed that I needed to completely disconnect the stock Pontiac resistor (double wire). Removed that resistor wire (as everyone said to do above) and showed a full 12 volts constant.

Took the car for a drive today. Car ran well much longer than before but still showed the same signs of misfire / dead spark feeling after about 10 miles of driving. Got home and touched the coil. Burnt my finger.

I hate to buy parts without clear and certain diagnoses... but coils seem somewhat inexpensive.

So which coil should I get? Blaster 2. Blaster 3. I don’t think I need an ignition box...

Thanks again,
Matt

[TedRamAirII]

MSD 2 coil is .7 ohms primary resistance. What does your coil ohm out to? I think you NEED a resistor with that coil. Maybe not...looking at the diagram they have. Be sure your BLACK wire has a good ground. You can verify this by checking the voltage while its running, should be 0-ZERO Volts dc

[george kujanski]

Again, use the coil recommended for use with the distributor.

George