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Delco Coils and Ignition Control Module Modification


wufibug

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My Magnavox unit failed and I decided to replace it with the separate coil packs.  This required changing the ignition control module to one that accepts the separate coils, but also takes the Magnavox style single connector.  The Magnavox sealed case has 3 screws built into it that fit the Reatta module mount.  The new module did not come with screws.  Has anyone mounted one of these separate coil modules that uses the Magnavox plug and if so how did you do it?

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The Delco style ignition is a three layer design. The top side is the coils, the middle is the ICM and the bottom is a mounting plate that bolts to the engine casting with three studs that are separate parts. As a matter of fact, the coils do not bolt onto the ICM. The six screws extend through the ICM into the base plate with the ICM sandwiched in between.

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I'm going to have to look more closely at the Delco style module I got and my old Magnavox to see if I can use the Magnavox base together with the new Module.  The new module, as below, did not come with a baseplate.  

ACDelco Ignition Module D1946A (10456478) NOS - Picture 3 of 6

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8 hours ago, wufibug said:

I'm going to have to look more closely at the Delco style module I got and my old Magnavox to see if I can use the Magnavox base together with the new Module.  The new module, as below, did not come with a baseplate.  

ACDelco Ignition Module D1946A (10456478) NOS - Picture 3 of 6

If you mean using the Magnavox ICM AS the baseplate, I don't believe that will work. The spacing of the fasteners for the coils is in the wrong place to mate up to the Magnavox coilpack screws. I do believe it would be very doable to make your own baseplate with a piece of 1/4" aluminum barstock about 3 1/2" x 5 1/2". Drill and tap for studs out the bottom and tap on top for the six coil mount screws. The thread doesn't matter as long as you have mating screws.

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  • 2 weeks later...

If I make an aluminum baseplate can I mount the Delco style module directly on it? Are there heat issues such that leaving some open space under the module is advisable?  Should I lather some dielectric grease between the baseplate and the module? 

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5 hours ago, wufibug said:

If I make an aluminum baseplate can I mount the Delco style module directly on it? Are there heat issues such that leaving some open space under the module is advisable?  Should I lather some dielectric grease between the baseplate and the module? 

The factory baseplate is a solid piece, no reliefs or vents for airflow. To grease or not to grease gets bandied about and I do not know if it is good or bad. I do know, I have never seen a recommendation to add grease in the FSM or found an original in the parts yard that was greased?

 

When I have my turbo engine installed, I relocate the ignition assembly by rotating it 90* for harness clearance to the exhaust piping. To do so, I made a plate that supports the ICM which extends out beyond the factory mount, but sideways, to provide the ICM studs something to connect to. This is the Magnavox style, but it has operated in that configuration for going on two decades. Oh, and no grease used.

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6 hours ago, wufibug said:

Are there heat issues such that leaving some open space under the module is advisable? 

Speaking generally, heat is the enemy of any electronic component, and that module is switching quite a few amps. I worked for many years as a quality engineer for a company that specialized in thermally conductive adhesives and greases, and in my opinion, the longevity of your application could not help but be improved by improving heat transfer.

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7 hours ago, Lee H said:

Speaking generally, heat is the enemy of any electronic component, and that module is switching quite a few amps. I worked for many years as a quality engineer for a company that specialized in thermally conductive adhesives and greases, and in my opinion, the longevity of your application could not help but be improved by improving heat transfer.

I agree completely about the need to heat sink most electronic components. This is one of those things that is an open question in my mind: Is the mounting bracket on the engine, warmer or cooler than the ICM itself? I have never done so, but always intended to measure the temperatures of the components to see what's what. 🙃

Edited by 2seater (see edit history)
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Unless there is a heat sink built into the module, I think you’ll find it runs hotter than engine temperature (May depend on RPM/load, so testing at idle may not be valid). 125C (257F) is a pretty typical temp for the life testing of components like this, and that is higher than typical engine temperature. And you are typically OK below that rated temp, although cooler is always better.

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The Magnavox case had a bit of heat sink built into the bottom.  I am trying to use that base after having removed all the internals and cut down the sides to about 1/4".  That 1/4" between the bottom the case and the sides where the Delco style module would sit would provide some cooling. The Magnavox case itself would be mounted to the baseplate as before albeit using shorter screws.  I could either support the module on the rails of the Magnavox case and bolt thru to the bottom of the case using spacers which would have the advantage of having that cooling space below the module or fabricate a thin aluminum "cover" for the Magnavox base and mount the module to that with a layer of dielectric grease in between.  Not sure which is preferable.

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You are in uncharted territory but I admire the creativity🙃 Is there enough material to run bolts through the coils, into the baseplate and sandwich the ICM in between? Actually I am not sure the method of clamping everything together really matters as long as it is solid mechanically and electrically. As far as I know, both greased and non-greased has been used successfully. Any question of longevity is probably hard to answer since the time spans are long.

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The Magnavox coil pack wiring scheme is:

     Top
    6 - 3
    5 - 2
    4 - 1
Harness connector end

 

Not sure how this translates to the Delco vertical arrangement.  I'm guessing it would be: 

     Top

      6

      3

      5

      2

      4

      1

Harness end

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Nope, your first diagram is correct as long as the harness connection is at the bottom relative to the diagram. It does not matter which terminal is connected to each coil as long as they are paired on the correct coil. They both fire at the same time as one complete circuit. 

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6 hours ago, 2seater said:

They both fire at the same time as one complete circuit

They call it a "wasted spark" system.  It wears out your spark plugs twice as fast!  ;)

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3 minutes ago, EmTee said:

They call it a "wasted spark" system.  It wears out your spark plugs twice as fast!  ;)

Yup, and they fire with reverse polarity to each other🤔

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