Small body HEI + MSD 6AL
 

Trying to wire up a 6AL with my Dave's small body HEI. I'd like to use the MSD because of the rev limiter and keep the HEI with a pigtail to use as a backup incase of a failure. Can anyone help? Here's what I've got:

Large Red - Power
Large Black - Ground
Small Red - Switched ignition?
Small White - ?
Small Black - Coil neg?
Small Orange - Coil pos?
Green/Purple Pigtail - ?

Thanks for the help.

Here's what the MSD says:

Power Cables: The heavy Red connects to the battery positive (+) terminal. The heavy Black connects
to the battery negative (-) terminal or other good engine ground.

Red: Connects to a switched 12 volts source.

Orange: Connects to the positive (+) terminal of the coil. This is the only wire that makes
electrical contact with the coil positive terminal.

Black: Connects to the negative (-) terminal of the coil. This is the only wire that makes
electrical contact with the coil negative terminal.

White: This is one of the wires that provides a trigger signal for the MSD. It connects to
the breaker points, electronic ignition amplifier output or to the Yellow wire of
an MSD timing accessory. When this wire is used, the Magnetic connector is not
(Violet and Green wires).

Violet and Green: These wires are routed together in one harness to form the magnetic pickup connector.

They plug directly into an MSD Distributor or Crank Trigger. The Violet wire
is positive (+) and the Green wire is negative (-). When they are used, the White
wire is not.

NOTE: MSD SCI Ignitions share the
same wiring as the 6-Series.


:)

Thanks for the help John - just got the same info from someone on the pro-touring forum. I guess one thing that's confusing me is that Dave uses a pigtail with the same connector MSD uses for their magnetic pickup. I guess I just need to sort that out versus using the white wire. I think I'll pull the distributor to get a better look at how the 4-prong module is hooked up, I can only see the one side when it's installed.

I need bring this one back - finally all wired up and I've got no spark. Here's what I've got:

Large Red - Battery Pos
Large Black - Battery Neg
Small Red - Switched ignition power
Small White - Not used
Small Black - Coil neg
Small Orange - Coil pos
Green/Purple Pigtail - distributor pickup coil via MSD GM HEI adapter

According to my timing light, I've got no juice. The HEI adapter can plug into the distributor output two ways and I've tried both with no success. Any ideas?

mwritter, this thread will be helpful for me at some point, since I have a Daves SBHEI and a MSD-6AL, too.

Just to clarify, are the cables you identified in the opening post OUTputs from the MSD?

What are the INput (power) cables to the MSD box? Could your no-spark condition be due to these cables? Is the MSD enclosure grounded? Should it be?

Engine-Ear - Thanks for the response. Yes, those are the 7 wires that exit the MSD box, counting the magnetic pickup connector (two-wire harness) as one. The box itself is mounted via 4 rubber isolators, but I have the ground wire hooked to battery neg per the instructions.

I'll have a look at mine and see if another set of eyes will help...

From what I remember, the MSD boxes can use the output of the pickup coil to trigger, (green/purple) or use the output of the module in the HEI (or points in a std dist). The MSD shouldn't care; it just uses a changing signal to trigger on.

If you are using the magnetic pickup signal and have no luck, reconnect the dist normally and use the coil output signal from the module (I believe that's the white wire).

george

Thanks for the input George - I'll hook the module back up and see if I can get a signal from the output via the white wire.