Msd 8207

Hello All,
I have a ‘77 C10, sbc400(406)/th350.

The truck was stripped when I got it. It had no engine wiring harness or distributor.
I installed the Summit ready to run distributor and a MSD 8207 blaster SS coil.
I’ve tried to wire this coil how they have in the installation manual but it doesn’t have spark that way.
The way it’s wired now, it fires up but won’t shut down. I have to choke/starve the carb with a towel to shut it down.
Anybody else running an 8207 coil alone without the msd ignition?
How did you wire the 12v ign?


Thanks!

I’ve got an 8207 but it’s wired with a 6AL, are you using a box?

nvrenuf said:

I’ve got an 8207 but it’s wired with a 6AL, are you using a box?

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No, sir. I am not. The 8207 manual says it’s not required.

How does your 8207 or box get 12v?
Which wire?

Do you use the wiring junction block on the firewall or no?

No, the 8207 doesn’t require a box but the wiring sources are different with vs without.

I use a 6AL box which supplies the + and - leads for the coil so I didn’t have to find sources from the truck.

As for my wiring, I have a secondary fuse block that supplies the constant and ignition 12v wires for the MSD box. This fuse box is powered by dedicated leads from a custom dash harness (literally a fraction of the original harness).

The coil just needs ignition switched positive and a ground, through the module or breaker points or whatever. And a ballast resistor if there's no current limiting in the distributor.

Tonimus said:

The coil just needs ignition switched positive and a ground, through the module or breaker points or whatever. And a ballast resistor if there's no current limiting in the distributor.

Click to expand...

Distributor doesn't regulate voltage to coil. And coil design itself is what determines if it needs external ballast,resistance wire or straight 12v.

Not talking voltage, but current. And that's straight from the instructions for the 8207.

So should I just run a wire from the unused ign tab in the cab to the coil?

You can.

Tonimus said:

Not talking voltage, but current. And that's straight from the instructions for the 8207.

Click to expand...

Again the distributor does not limit current the Ballast resistor,or resistance wire does. Again as I said the coil determines whether or not a resister is needed,8207 coil, is a coil that needs a resistor,unless used with a current limiting ignition system(msd box) not distributor. I read the instructions, the part about using a ballast resistor in series with factory resistors is incorrect. Call MSD help line if you want, to verify. Ask them if you are installing this on a 1968 Camaro do you keep the factory resister wire and install an external ballast. They will tell you no,because your voltage at the coil will only be about 5 volts. And the resistance wire,or external ballast does drop the voltage,that's its job. The problem with the instructions is they are too general.