DV or Don Scott

[Jim Downard]

Guys, I know you've probably done plenty so I need a little insight. I just received my MSD distributor, 6AL module, coil, and plug wires. How much of the existing Classic Roadsters engine harness can I use. It looks like I will have to tape off the old distributor wires. Is there a harness wire to power up the module or do I need to run dedicated switched power wires to the module. Also, how about hooking up the tach. I just want to know the most common method you guys use rathern that making a more difficult attemp.

I bumped up my MSD purchase by six months because the other day I took her for a spin and under moderate to severe load, on the left bank of cylinders I started to get what I believe to be one cylinder popping. At light loads just putting around town it doesn't do it. My old engine did this for a while out of the right bank of cylinders. My guess is problem in distributor/spark plug wire area.

Anyone else with advice, chime in.

Jim Downard

[Jack21]

Jim, am running similar setup. These are the things I did to install, and problems I ran into.

MSD dist: If vacuum advance, you'll need to replace the MSD non-adjustable cannister with an Accel adjustable for a '57 - '73 Delco. 16 deg vacuum advance is too much. Accel lets you adjust this down to 8 - 12 deg. You'll get a low load miss at 2300 - 2500 RPM if you don't do this. Too much combined advance. Dist centrifugal set to 20 deg at 2300 - 2600 RPM. If hydraulic roller cam, need to swap iron gear for steel one from FMS. If hydraulic flat tapet, leave it alone.

MSD Box has two power leads. Big red wire is power in. Connect to CR #111 as it exits the breaker. Small red wire is ignition in. This gets conected to the CR #128, which also powers the electric choke on the carb. CR ballast resistor, coil, and dist wiring is now history. Use MSD wires for coil & dist. No ballast resistor is used on the MSD.

Conventional ignition uses ballast resistor to drop run voltage down to 7 volts. MSD primary voltage is 460 - 480 volts, which gets stepped up to 40,000 - 50,000 volts by the coil.

CR tach lead is #132. This goes directly to MSD tach out connecter on box.

Potential problem, engine may continue to run with ignition off.

Solution #1. Put a diode in the alternator energize wire so power doesn't feed back through the ignition. If you didn't get one in the kit, it's a Radio Shack part, 3 amp 50 volt diode or rectifier. I'm using a Delco alternator, and the energize wire is easy to find. Externally regulated Fords may be more difficult. Guys with externally regulated Fords, help us out.

Solution #2. Wire both box power in circuits through relays so box is electrically dead with ignition off. Standard auto supply store 30 amp headlight relays work fine. Box draws 7 amps.

I butt splice, crimp, solder, grease, and shrink tube all electrical connections. Makes them vibration and corrosion proof. You can get butt joints without the plastic piece at Radio Shack. Otherwise, pull the plastic pieces off before use. Crimped only joints in engine compartment, and chassis will eventually vibrate loose, and/or corrode.

MSD advises against use of platinum tip spark plugs. Plain old Autolites for Ford motors.

[dscott]

Jim, Jack is correct on the wiring. Big red and black to the battery, small red to #128, #132 to tach output on MSD box, orange to coil +, black to coil-, twisted pair directly to dist. I don't use the GM alternator so I haven't had a problem with engine run on. With the Ford alt you won't have a problem. If you run an electric fan without a relay setup the engine will run on after the ignition is turned off.
Don

[Mr.Fixit]

I have seen the run-on problem with ford alternetors and MSD boxes. Just install a diode inline on the "I" terminal at the regulator.