Coils do not have a ground, and MSD works completely different from "conventional" ignition, that is, breaker points, Mopar breakerless, or GM HEI based systems
MSD works more like a photoflash. It charges up a Great Big high voltage capacitor with several hundred volts and when triggered, sends that pulse through the coil.
(By the way, THE ONLY wires of any kind you should have hooked to the coil, are the ones coming from the MSD box. No radio condenser, no tach, nothing else.)
So far as a "coil ground," with breaker points, the spark happens when the points open, so you have a series circuit there, from the coil primary, through the (distributor) "condenser" (capacitor) to ground.
The MSD may ground the coil by means of the coil NEG wire which comes from the MSD, that is, the pulse would be applied across the coil NEG and POS terminals, the NEG being grounded by the MSD internal wiring.
One other thing. How exactly, and I do mean EXACTLY, are you checking spark?
You may have a bad (internally burned) coil wire?
This is a breakerless distributor. Im checking spark by holding plug to header bolt and watching spark from electrode to grnd strap.
I did just remember that the heads were painted off the motor so head bolts aren't making much if any connection. Couldn't paint over them pretty arp bolts :roll:. Probably compromised torque accuracy as well :/. So far so good, then again its only 9.5:1 NA and no bottle. Im guessing the plugs on the right bank are making a halfass connection but the left bank is probably poor.
The problem Im having is ever since I put the motor in after break-in its had intermittent spark issues. When I first installed the motor, it was on the orange box and ballast. It broke in fine but on its maiden shakedown it died and would not start, had no spark. I replaced the orange box with a new black. That fixed it temporarily, but soon after it failed to spark, so then I thought I got a faulty box so exchanged it for a silver, but still nothing. Then I bypassed the ballast and it fixed it temporarily. Then it would intermittently have spark, but even when it did have spark it wouldn't fire.
Then I put in the msd, that seemed to fix it, started right up. Put probably 700-900 miles b4 I put headers on and drove it with wide open headers to the exhaust shop to have my ds pipe re-done but not installed. Made it to the shop, but then it died on the way back like it was running out of fuel, sputtered then died and would not start. I checked for spark and fuel (strong pump shot). I thought maybe I got bad gas, tried ether to no avail. I pulled the plugs and all were chocolate brown, but # 5&7 were lil wet with fuel. So out of ideas, I put in fresh set and it fired right up, got me 20-30 blocks and same thing, sputters and dies. So again I check spark, tried ether, nothin. Pulled the plugs, all where white
/ I know) and dry.
I called my pops for a tow, he looks at the spark and says its not very strong, looks bright orange, should be bright blue/white.
So that's the current conclusion...
Despite the paint and gaskets insulating the head/bolts (especially the left bank), the LB never fouled or showed uneven color to the RB. The only plug that showed a lil color was #1. So my guess is the intake manifold bolts (even with thread sealer) are passing current. So maybe the paint isn't the issue. Just a thought.
Sorry for the long winded reply, I tried to make it short as I could.
