The 1st box was explained to me as being a bad chassis ground and I need to ground it to the negative terminal on the battery....ummm, wrong answer. The first box smoked with only the power lead connected and ground lead connected so something was way wrong.

The second box started smoking again only this time with the power lead disconnected and the 12v jumper plugged into the fuse box to supply power to the box when the key's in the on position.

(I'm running a GM HEI 4-pin module ignition)

I'm thinking there may be an incompatibility with my Accel Super Coil. Everytime the box started smoking the coil wires (+ and a -) that are connected to the cap became almost too hot to touch. The smoking stopped as soon as I unplugged them. There is also an engine ground that plugs into the cap and that didn't seem to make a difference, but I'm leaving it out as a possiblity. For the time being I attached the engine ground to a random bolt holding it to an unpainted part of the engine.

So I see 2 possibilities that are killing these things:

1) I need a good engine strap
2) My accell super coil does not work with an msd digital 6 box.


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1990 GTA
-355 carb'd, nicely reworked '64 vette heads, 2500 stall, 4.10's, other small things.
-Alston SFC's, Eibach Pro-kit, Koni's all around
-100+ nitrous shot
-Cruising in style with leather and nice stereo.

 

This I'd believe, it's not a good idea to mix and match ignition components. Which Super Coil do you have? I think most of them are designed for inductive ignition systems, and not all of them work with capacitive discharge systems like the MSD.

 

When switching to cd ignition, the coil ground becomes engine ground. From the factory the module switches the coil - (floating ground) which also drives the tach. This is why cd boxes have a seperate tach output.

The cd box puts out over 500v on the + coil wire so a cd coil is needed as the coil impedance from the stock 12v system is totally different.

So it could be the coil, or it may be wired wrong. I would go with a complete MSD system for the MSD box and check the wires over. Also run at least 12 guage wires between the coil - and both cylinder heads.

 

does that mean that the coil ground wire is supposed to be grounded to the engine or to the chassis?

[This message has been edited by crazeinc (edited August 03, 2001).]

 

Both.... In the old system the - coil connection is sepeate any ground in the car (except the tach) and the + coil is always hot with the key in the ign. The reverse is true with a cd system, the negative is body, frame, motor grounded (thus the tach will not work) but the +coil is switched on and off @ over 500v from the spark box so now the +coil is "floated" from the rest of the ignition. This is why cd box makers specify the coil to use. Grounding the coil - to the heads just reduces the resistance from the coil to the plugs giving you a better spark. I have the Holley strip annihilator system and used the holley pro strip coil and grounded the -coil to the body where the coil is mounted, and ran ground straps to both heads as they recommend. You shouldn't use a inductive dischage coil with them although some people got away with it somehow.... Isn't the reason you got the spark box is for better output? A stock type coil is seriously defeating the purpose. Also use spriral wires...

I hope this helps.. It's kinda complicated in my car (your prolly is the same) where the module fires the computer which changes the timing by altering the pulse width which comes back to the module to fire the coil (which now fires the cd box as a - signal, where the cd box fires a pulse of +500 volts to the + side of the coil while making a - square wave signal to work the tach)

 

it makes sense, but they never said anything about needing a new coil for a CD ignition. I'll call them up on monday and see what they have to say about it.