changing from points to electronic

[MadScientistMat]

I read the write up of putting the GM module in the ignition. Is that the same for any Mopar engine?

It's the same for pre-Lean Burn slant sixes, small blocks, and big blocks. I've heard it's also the same for Australian hemi sixes. For other engines, you would have a bit more difficulty.

Say I used an MSD 6A box, would that negate the need for the resistor and ECU? Or does the box simply amplify the signal that's sent out by the ECU?

The box negates the nead for either one. It can trigger off the pick-up coil in the stock distributor and bypass the rest of the system.

 

[memike]

I have it installed and running great and starts up quickly.
I started a members restoration thread with pictures.
Thanks again for you help on this.

memike.

 

[dgc333]

Are you serious or being sarcastic? Say I used an MSD 6A box, would that negate the need for the resistor and ECU? Or does the box simply amplify the signal that's sent out by the ECU?

Not being sarcastic at all. Using a GM HEI module in place of the mopar ecu does not allow the elimination of the ballast resistor. An MSD box is a completely differnt beast. It will trigger off the points or magnetic pick-up in the distributor and fires the coil directly from the box. The ballast resistor is not required with an MSD.

 

[Johnny Dart]

never understood why people were so enthralled in getting rid of the ballast resistor?
or why they wanted to go the GM route.........etc, etc...

I have never (knock on wood) had a problem with the Chrysler system (dist, ballast resistor, ecu,voltage reg,) etc.
Seems the guys that have the problems are the ones that go away from Chrysler design, and start adding generation X parts, off the shelf parts and pulling there chrysler parts.:-k

 

[dgc333]

A ballast resistor is a superior design to either a fixed power resistor (or resistor wire) or to a coil thats internal resistance is sufficient to allow it to operate a full battery voltage.

Besides the obvious of allowing it to be bypassed during starting for a hotter spark the ballast changes its resistance over the operating rpm range to compensate for the reduced output of an inductive ignition as the rpm goes up.

An inductive ignition works based on a collapsing magnetic field in the primaries of the coil by the points opening or an electronic module switching the current flow off. To get max potential from the coil the current needs to flow for a given amount of time to saturate the secondary windings. But as the rpm goes up the time for the saturation to occur goes down and so does the potential output. This can be compensated for by increasing the voltage in the primaries. If you increase the voltage so you get reliable ignition at high rpms there is to much current flowing at that voltage at low rpms that can result in damage to the coil from over heating.

A ballast by definition changes its resistance with temperature, the hotter it gets the higher the resistance. So the ballast resistor at low rpms has current flowing for longer periods of time between firings so the resistance goes up thus limiting the voltage and current to a safe level. At higher rpms the current is flowing for shorter periods of time so it does not get as hot and it allows more voltage to the coil.

The GM HEI system uses a completely different coil design that is less susceptible to over heating so it can be designed to provide adequate output at high rpms without the danger of over heating at low rpms. Use a GM module with a Mopar coil without a ballast and you are over stressing the coil and reducing its reliability.

The more modern electronic ignitions normally use an E-core coil that is more like the original GM HEI coil and the electronic modules are more sophisticated and can control the current flow by adjusting the dwell (the time the current is flowing) over the rpm range.

 

[blasphemous]

My main reason for wanting to go with an MSD box is out of simplicity. Althought your post was a little hard to follow, I got the basics of what you were saying. The system actually makes alot more sense now. I had no idea what the ballast resistor was for to be honest. I'm more confident in my knowledge of the ignition system now. That answered what I was attempting to figure out! Thanks for being patient w/ me.

 

[MadScientistMat]

I thought the HEI modules adjusted the dwell angle as a function of RPM, like newer computer controlled ignitions. (Then again, the HEI module I'm using myself is a later computer controlled type - I'm not 100% sure if earlier ones have this function.) However, their dwell angle is for a specific coil, so this does not get around the fact that you're not supposed to pair a HEI module with a stock Mopar coil and no balast resistor.

 

[memike]

Bringing this thread back to life again :icon_smi:

We all know why, mother natures :evil5: hand has touched her (lightning)
I love this great site and just re-upped my gold membership 8-)
Well Treva did thank you hun :love8:

 

[memike]

Mother nature did not stop me, I just pulled the coil and ecu off of my truck after I got it wired back up, I did not have to spend $80 dolors that day.
I carry a spare everything Voltage regulator that works and a ecu used that works ballist resister also, so if any thing fails I don't have to spend $80 or more dolors. Thank you mother MoPar