I have set up a 12a with direct fire using 2 blaster coils and a MSD. I'm running trailing with the dizzy.

The set up will not start with the trailing plugs firing.

After confirming TDC with the flywheel and restabing the dizzy, the engine starts with the trailing disabled.

When I check the timing, the front leading plug has the timing marks 90 degrees off on the carb side of the engine. When I checked the trailing front plug the timing marks are right on(used a spark plug grounded to neg).

On a road test, car was drivable, but stumbled at 4k.

I'm going to reverse the polarity on the pick up for the leading, to what happens?

Can't understand how the leading can be out bt 90 degrees and still run properly.

The direct fire messes up the timing light as is, timing light tach is off.

Any one with direct fire MSD run into this one???

 

Got it beat!

Reversed the polarity on the wires for the leading ignition to the MSD and she settled right down.

Connected up the trailing plugs. Dialed in the timing. Idle is around 1100. 4 k stumble is gone.

Exhaust is damn loud with this half bridge. Running dual 2 inch ti 3inch over the axel with a magnaflow. May need to quiet it down a bit.

For now smiles. It drives.