i am rebuilding a 400ci engine. I have just bought a distributor from summit (https://www.summitracing.com/parts/SUM-850026) however my truck has a computer module from the factory that hooks into the old distributor. What does this module do? I understand the distributor rotates with the engine and tells which spark plug to fire. i understand that in modern cars they have a module in the car to tell which spark plug to fire and no distributor. But how does my truck have both and what advantages does it have? would it be fine to run this distributor without the module or would you get a distributor that is compatible with the factory module?

Thanks! hopefully you get what i am trying to ask.

MSD Ignition 8362K: Street Fire Ignition Kit Small Block Chevy | JEGS basically what is the module in this kit doing?

 

There's no computer of any kind on these trucks. Inside the original DuraSpark distributor is this:

D4PZ-12A112-A .. Stator aka magnetic pickup coil-takes the place of the points & condenser (Motorcraft DU-1A).

1974/79 V8 FoMoCo Passenger Cars/F100/350's, Bronco's & Econolines with DuraSpark electronic ignition.

 

well i assumed it came from factory atleast. it looks as old as the truck and i thought my proffessor said it was from the factory but then again that was awhile old and my memory could definitely be better. So is there a con to not running the module vs running one with?

 

You won't need the module, as the HEI already has its own, built into the distributor.

Personally, I'd rather run an OEM-style dizzy from the McParts store, and use the factory module. Does it say "Duraspark" on it? If so, don't throw it away if you stick with the HEI.

 

They don't even teach anything in the auto mechanics classes at the high schools anymore (at least in our area) anything about distributors, points etc...anymore. They've even thrown away the Sun Distributor machines that they use to have.

Later, Shortbox4x4

 

Indeed...graduates of automotive schools are not mechanics-they are technicians. Years back, my brown truck broke down on the road, and I had it towed to the local Ford dealer. They had to wait for the "grey hair" to get back from vacation, cuz the younger guys didn't know what a curburetor was.

Even the grey hair was guessing. The truck broke down ten miles from home, at a stop light. The guesses were:

• Bad gas (after a fillup at chevron)
• Plug wires in wrong order
• Timing 180* out
• Trouble with the duraspark system

One week and $900 later, I had another tow truck move it to my driveway. I put the plug wires back and it fired right up. Has run fine ever since.

Wish I knew then what I know now. And sorry for the hijack

Anyway, the factory distributor and ignition module are perfectly good units. That being said, the ignition module is one of the items that occasionally go bad. Unfortunately, they don't just die-they cause a bunch of weird problems, most notably hard or impossible starting when hot.

The primary advantage to HEI distributors is to clean up the wiring. Distributor, coil and ignition in one tidy package. That's also the con-if it fails in the booneys, you're screwed

 

So would you stock with the HEI distributor that i bought to clean up the wiring? It isnt a daily driver or anything its just a fun expensive toy. So if it breaks down and i can drive it for a few weeks until i fix it, that wong be an issue. Would an old module like that be worth any money?

 

You are right about schools not teaching kids this stuff. I am in automotive engineering technologies major and we covered distributors in about a class to understand the basic principle of how they work. We are taught to replace not repair.

 

For a toy, and the "cool" factor, nothing wrong with the HEI. In fact, I'd bought one for one of my trucks, but it didn't clear the air filter.

With fewer parts scattered about the engine compartment, the HEI might even be more reliable. After all, Chevy has shown that it does actually work...

If I were gonna install the HEI, I'd get the one made with Chevy parts, so if something went wrong, i could get parts anywhere.

 

You can also use the HEI module in conjunction with the Duraspark dizzy for a slightly cleaner install. The tiny module is easily hidden and will likely live longer, remotely mounted with a proper heat sink.
But that Summit dizzy is probably a pretty nice piece.

 

I will say the summit distributor definitely looks good. Buy it HUGE i m worried about it fitting. Hopefully everything works out.

 

The Ford Dura Spark is a very good unit. It's what MSD based they're distributors and ignitions set up's off of. You can buy a little pigtail harness connector from MSD and hook up they're MSD 6 ignition controllers to the factory Ford Duraspark distributor. The harness is MSD Wire Adapters 8869.

Later, Shortbox4x4

 

Since you have the HEI in your hands, install is easy. Line up #1 cylinder on the intake stroke. Swap out distributors. Run a line from the 'I' terminal on the starter solenoid over to the distributor and splice into your 'RUN' wire to distributor. You will need to determine which wire that is. Just remember that the wire going to your coil does not supply 12volts and that may not be enough to run the HEI. As for room, you will need to either raise the carb or get an aftermarket cleaner. Of more importance, you will need to get a different gooseneck for the thermostat. Otherwise the HEI will not go in correctly. They have those at Summit also.

 

i would buy a dist that is stock to the engine family, distributors are not something i like to mess with other than the vac advance distributors that are easier to adjust. i would get a stock dist or find a way to bypass the original system.

 

It seems to me that there will be plenty of room for it off my memory. But who knows. So if i supply 12v to the HEI it wont power it enough is what your saying?