External mount HEI module

Some of you probably know this but I thought this might help some people. I have had an MSD billet distributor control box quit and had heard of using a factory Mopar box. I did an internet search and found that but also a few on external HEI modules. The Ford Duraspark is notorious for Control box failure( especially cheap auto store replacements).Any magnetic trigger distributor will work. The MSD has 2 black wires and I couldn't tell which way to hook it up and a site for Nissans said to try both ways and the one that is retarded is the right way. It works Great! A friends T bucket with Buick V6 is also using it.

The four HEI module terminals are labeled W, G, B and C.

W = positive lead (+) from the pickup
G = negative lead (-) from the pickup
C = negative side (-) of the coil
B = positive side (+) of the coil

FWIW the same module is used in all of these cars ACDELCO P/N D1906

AMERICAN (1980 - 1981)
BUICK (1974 - 1987)
CADILLAC (1974 - 1980)
CHECKER (1975 - 1977)
CHEVROLET (1974 - 1989)
FIAT (1977 - 1982)
GMC (1975 - 1989)
JEEP (1980 - 1981)
LANCIA (1976 - 1979)
MGB (1980)
OLDSMOBILE (1974 - 1987)
PEUGEOT (1977 - 1981)
PONTIAC (1974 - 1987)
RENAULT (1979 - 1982)

Thanks for the additional info Larry. Also use an aluminum plate under it with heat sink paste. I used the HD heat shrink spade terminals and 12 gauge wire. One of the spade terminals is a smaller size. It doesn't use a resistance wire either. It would probaly be a good idea to use a relay for the ignition to insure you get full battery voltage.

One other interesting note, these are the same modules that are in the Moss Amplifier Assembly p/n 142-975 http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=29065#19 @ $329.95 a pop. You open the can up and you find the module mounted with thermal grease, two screws and 4 wire jumpers. Given the price ot the other parts, the can and labor to assemble it must be reallllly expensive. :)

Looks like this is a case of the famous Hi Tech outlook: " Knowledge is power--to rob "

Actually the Moss box can be bought used cheap on Ebay. They were used on 1980 MGBs with the 45DM distributor, as well as a lot of Triumphs and Jaguars. Since it mounts neaty under the coil and keeps water out, its a good idea to use the well made aluminum box that Lucas produced.

Jeff,

That's good info on the can. I always thought the can was well made. I just thought that the whole assembly was overpriced once I got inside one,

Sounds like an opportunity to offer remanufactured parts for something substantially less and still make a good margin...

I carry one for spare just in case my MSD box fails. I also used the modules externally on my race cars that had similar system. Reason why it was used externally, was to keep it cool away from heat, which is one of the reasons why they fail. I had two in series separated by a toggle sw just in case of a failure in one of the modules.

Also keep in mind that there a differences in the modules from one engine to another, all ofthem look the same, but not created equal.

Bill, can you explain the differences? The 4-pin HEI module is kind of generic. The same one was used on 4,6, and 8 cyl American cars. Then there's a diode and an old Lucas condenser in the box. That's it. What am I missing? I guess there were polarity changes in the wiring to the pickup coil, otherwise that should be the only difference. Its kind of like how the Crane XR-700 box is universal, just change the signal from inside the distributor to suit the engine.

The way it was explain to me Jeff, is that some of the modules have different duwell. Talking to Crane when they used to have the high performance modules, they had a different part # for the V6 and V8. So... I am only going by what I was told by Crane.

Now...from the practical side. my 3.8 Buick V6 did not run well when I installed a V8 module, yes it did run and could drive it etc.
Thinking that they all were the same, after all they all look the same. My 3.8 V6 ran much better with the V6 module.
That was my experience. Today perhaps all modules are the same? not sure.

Interesting. That makes sense to some degree. The XR-7000 box has intelligent dwell. I thought the HEI modules did too, but never checked. I guess I have a project...

The early HEI module(original equipment untill early 80's?) was found to be weak over 4500 RPM and lower amps, shorter dwell.People blamed the coil in cap.The ones you buy now are supposed to be good to 7000+. Maybe Bill had an early V8 one and the V6 one was the newer module.