The HEI module is a generic 1975 module from any parts store. (4 pin)

I only carry mine as a spare in case my amp fails which is unlikely.

If you're going to try an HEI to see if you can get yours started, then you only need to "hang the module in space" and connect the wires as the diagram indicates. I did mount a heat sink to the module, not sure how hot it gets. For short term testing, you would not need the heat sink.

(Be sure to run a ground to the module)

Did you get sorted out if you have true battery power from your ignition wire? If you use the resistance wire to supply the +12 to the HEI module, I doubt it will work. The HEI modules are very power hungry.

I power mine from the horn relay bus bar, lots of power there. Use a 12 gauge wire

 

That seems reasonable. There's no technical reason why removing a correctly functioning starter shunt connection should make any difference/improvement in starting an engine. (The shunt circuit's main job is to compensate for low battery voltage cranking on cold days.)

 

These modules are not power hungry. There's a very small integrated circuit in the module that reads the magnetic pickup signal and then turns on a power transistor to drive the coil. The coil is the item that requires multiple amps to function correctly (ie: store energy for transfer to the spark plug).

 

i jumpered a wire wire from the horn relay to the white wire of the ti harness to get 12.4v. The pink wire from my ignition switch is resisted. I would consider tearing my dash apart to plug the white wire directly into the ignition block if I could get the system started. At this point not sure if TI is doable. So with the HEI can I use the TI distributor or do I need some other modification.

 

You are absolutely correct, however with the starter wire connected, while cranking I would get spark, (from the coil) only it was highly intermittent. If the intermittent spark hit at the right time, the engine would start. Several revolutions.

With the wire disconnected, I get steady regular spark. Engine now starts with the starter barely engaging, usually in one revolution. Go figure...

 

The use of the HEI module is used with the stock TI distributor, no modifications needed. Nothing else is used from the TI setup.

 

Thanks barry

 

I used the term (power hungry) generically, I know the module is an IC. It does not change the fact that you need to supply an HEI setup with good power.

 

Have you tried pulling the coil wire out of the distributor cap, and placing the end near a ground so that you can look for a spark while cranking?This would supply some information on where the problem might be.

Also do you have access to a couple simple parts like resistors and LEDs? I was thinking you could disconnect the coil C+ wire and have the module drive the LED instead of the coil, and you could do some cranking (or just momentarily shorting the white/green (?) distributor lead to see if the module correctly shuts off the current to the LED.

The TI system is very simple compared to later ignitions. It's easy to do some simple test debugging on it.

 

69427,

Ill pull the distributor wire and check for spark tomorrow. I don’t have resistors or LED but I’m sure I could buy some.

 

Good power and power hungry are not synonymous.

 

Ok, lets get technical, a HEI circuit needs "lots" of amps. How's that ?

 

"Lots", compared to what? Quick and easy math below:

The TI system uses a low inductance coil. To get enough energy into a low inductance coil requires a lot of amperage. The TI system runs about 7 amps (about 85 watts) in an 80% duty cycle when driving down the road. Average wattage: 68 watts.

An HEI system, with a slightly higher inductance coil, runs at a lower current 5.6 amps (about 67 watts), but at about a 30% duty cycle driving down the road. Average wattage: 20 watts.

A points setup typically runs at 4 amps (about 50 watts), and at a 67% duty cycle. Average wattage: 33 watts.

The HEI system is a remarkably efficient ignition system.

The Ignition Physics sticky explains all this.

 

69427,

would you you mind taking a photo of your HEI setup?

 

That was actually a joke, however thanks for the information.

I have seen people upgrade from points to an HEI dist and try to use the resistance wire feed and have problems until they eliminate the resistance wire.

 

Here's a couple of old pictures that fortunately weren't stored on photobucket. The HEI module is attached to a small piece of 1/4" aluminum, which is then bolted to the ignition shielding in the open space between the distributor and the original coil. For those very observant readers, these HEI electronics are in a different physical molded package, but it's the same guts as every other four terminal module. (This module housing was for a foreign customer who wanted the HEI electronics, but in a housing more suitable to their own wiring harness.)



This is a non-Corvette distributor that I converted to use a magnetic pickup coil (using Chrysler parts), but it is identical to the guts in my stock '69 distributor. I converted the ignition to electronic decades ago, using parts from a Hays Magna-Pulse system, but after a few years the ignition box started to take a powder, so I threw it in the trash and hooked up the HEI module between the distributor pickup coil and the stock points coil. Other than running a non-resistive wire through the firewall it was a simple wiring hookup job.

 

Nice setup, are you using a point coil or the TI coil ?

 

The stock 48 year old points coil. The HEI module allows a bit more primary current to flow through the coil, so the net result is a bit more spark energy. Great plug life compared to my old points setup. I have several other points type coils on the shelf that I've been curious about testing on my Sun machine and possibly swapping onto the engine, but lack of time and lack of a good reason to fix something that ain't broke have put that particular exercise on hold.

The TI coil has less inductance than the points coil, so if you run an HEI module there is less primary current charging the coil at lower RPMs compared to the TI module. Lower current results in lower energy to the plugs. However, at higher RPMs the lack of ballast resistors in an HEI controlled system lets the coil charge up quicker, possibly duplicating or exceeding the energy levels of the TI system. One of these days I'll have to do the math just to satisfy my curiosity on this.

FWIW, a bunch of years ago I put an HEI module in a buddy's '67 BB after the TI module crapped out (he kept the TI coil in the circuit for cost reasons). He ran the car for several years after that (street and autocross), and was quite happy with the ignition system despite the slight mismatch of parts.

 

I wish I knew about this HEI module conversion earlier this year. But no. I just had to remove the msd box, buy new TI harnesses, blow out 2 modules, buy a 3rd module, new module decal, lengthen the distributor box mounting brackets to fit the oem TI coil. If my TI craps out anytime in the future, this is the way I'm going. Is it really as simple as mounting the module, wiring as shown previously, stock points coil, and some wires and terminals? Do you use some sort of heat sink grease, like used for computer cpu's, under the module?

 

It's pretty straightforward. The hardest or most expensive part is having a distributor with the magnetic pickup coil in it (or converting the points distributor to a magnetic pickup). A new C+ wire to replace/shunt the ballast resistance in the harness, and some wires/connectors to hook into the HEI module. And of course, some heak sink grease for the bottom of the module.