I was going through some spare parts the other day and I saw an old '70s Chrysler electronic ignition ECU. I was wondering if anyone had ever placed an HEI module in there to hide the GM parts on their mopar? Or any tricks others have used to hide their HEI setups?

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'66 Dodge Dart

Yes, it's been done -- usually with less-than-good results, but still I admire those who do it, because it means they've finished everything on their to-do list more important than "hide GM parts on my Mopar because otherwise someone might see and it really seriously OMG totally matters for realz".

I'm being snarky, but...seriously, now, why on earth does it matter? Who are you worried might see a non-Mopar part on your car (eek!), what are you worried they might say or do, and why do you care if some dumb yutz points and goes "Ha-ha, you have a non-Mopar part on your car!"?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I didn't mean to ruffle your feathers, Dan. I don't really show off my engine to anybody, so its mostly for myself. It just seemed like it would be a fun project and I like my car to look more-or-less stock with fewer visible upgrades.

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'66 Dodge Dart

For a V8 HEI application, there is a guy maiking a mounting bracket/heat sink, allowing you to place the HEI module on the underside of the distributor. Space makes that difficult (impossible) on a SL6. But you are free to put the module anywhere you like, as long as it is attached to some surface that can act as a heat sink. Then all the original wires to the stock Mopar ECU can be left alone, just cut and taped to the new ones to look as splices. You can then disconnect all wires giving power to the original ignition setup at the ignition switch, where it is invisible.

It may also be set up as the perfect anti-theft device, imagine a car thief desperately trying to start the car by using a jump-wire to the original ignition!

Olaf.

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Aspenized

Olaf, I've seen the dizzy bracket and every time it comes up I try to trick myself into thinking it would work. But as is always stated, too low, too wet, too cramped down there

My first thought is to mount the HEI module under a stripped out '70s Chrysler box, using the wires from a 4-pin harness for the module. However, I'm a bit worried about cooling, especially with the restricted airflow. If anyone has thoughts on safe mounting locations that would make it appear more like a points setup that would be awesome.

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'66 Dodge Dart

Heat transfer is through the back of the module, not the front; it can be covered up as long as it's adequately heatsinked (heatsunk) at the back. Remember, in its native environment it lives inside a distributor and is heatsanked to the distributor body.

The bigger problem with remote mounting of the module is RFI/EMI on the distributor-to-module wires lousing up the signal and causing running/driveability problems. It's not an impossible obstacle to overcome (and shielded wiring would be the ultra-super-duper way of solving it); see here and then read back up to the beginning of the thread. 440_Magnum is a highly accomplished electrical engineer; listen to his advice.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the input Dan, and pointing to that thread which has lots of good discussion. I've read that you suggest mounting the module to an aluminium sheet and mounting that to the inner fender. Is the inner fender not a very good heat sink on its own? Also, I've considered sandwiching the fender with an aluminium sheet (as mentioned in the HEI setup thread), but I'm not sure how much clearance I'll have under the empty ECU. The other thought was to sandwich the inner fender with the HEI module and some kind of heatsink.

I'm also curious if there is a max. distance I'll want to mount the module away from the distributor and coil, thinking latency issues.

Also, with coil selection, are there any that look more-or-less like the old can style but will work well with HEI? I'm guessing no, but might as well ask.

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'66 Dodge Dart

Josh P, here is the number for the original ACDelco aluminum module mounting bracket with cooling fins: ACDelco 10474610 heat sink. Other auto shops probably have it in stock too. (local chebby dealer?)

You can take a look at my setup in this thread: Gm Hei Module Conversion Troubles. As you see, I have mounted all together, and the wires between module and distributor runs along/amidst the spark plug wires, no problems at all. But then again, I have the good Magnecor spark plug wires.

There are coils avalable of the canister style that should suit HEI just fine, any coil with a primary resistance of 0.5 Ohm is OK. That is the resistance you measure between the negative and positive input posts on the coil. You could browse the posts here over the last couple of weeks, another member asked about the same thing recently.

Olaf.

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Aspenized

You can find many coils that will work "OK" with HEI, but it's harder to find a can-type coil that will work correctly with HEI. There's a list of factors beyond the coil's primary resistance that come into play. If you must have a can-type coil, the item from a Ford Duraspark system probably comes closest to meeting the performance specs around which the HEI system was designed. Problem is, most of the Duraspark coils use snap-on primary terminals rather than the threaded stud-and-nut terminals on your present coil. This isn't hard to work around; the unitized snap-on connector is available as a repair part.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I mounted my HEI to a 1/4" aluminum plate and bolted it to the fender. I covered the mess of wiring on the fender with a cosmetic cover, with holes drilled in it right over the hei. The cover is open at the front and rear to allow air flow. So far it has worked fine. I am still experiencing some EMI interference between the distributor and the ECU somewhere at certain rpms and boost levels, so this is to be taken seriously.

The wires are actually fairly neat, there are just a bunch of them, and I take the car to shows where other cars look like you could eat off the engine bay parts. This cover was a slight bow to that influence.

Sam

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About how tall is the cosmetic cover you used? I'm a bit concerned about clearance since I'll be using a mopar ECU as my cosmetic box, and that doesn't provide a whole lot of extra room. The lack of room under a hollowed out mopar ECU has me thinking I won't be able to get a 1/4" of aluminium and the HEI module under there. So would the aluminium still have effect if I bolt it to the underside of the fender?

Also, I've been scrapping out a '70s ECU box and its got this rubber (it is also kind of grainy) covering all the electronics and it has been a real task to scrape it out. Does anybody know an easier way to remove that rubber glue stuff?

PS–Sam, in the link that Dan posted there is a suggestion to twist the two wires that lead to the distributor. Have you tried that?

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'66 Dodge Dart

Can't hurt:

Look here and here for reason to twist conductors.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

The wires from the VR to the HEI are shielded microphone cable. From the HEI to the ECU they are twisted. I have just tracked down 20 gauge shielded, twisted wire to go between the HEI and the ECU, and will order that soon.

I will go out and measure the height of my cosmetic cover,and get back to you.

Edit: It sits 1.5 inches above the fender. There are several fuse blocks under there as well.

Sam

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