cheap Mopar ignition upgrade

[UK-Winnie]

Not sure if this is the right part of the firum but I can’t see it has been covered before and I can see a lot of people on here appreciate the economy DIY approach so I thought I’d post it here.

This is a nice cost effective upgrade I did on one of my cars but it applies equally to all of the common Mopar electronic systems from early ‘70s onward.  Looking at when I first posted it on a musclecar forum I’ve been running this system since 2009 and it’s still going strong.

It basically involves changing the Mopar control box, ballast resister and coil for a GM style HEI module and suitable high energy coil (the ballast resistor is not required).

I did mine to look stock appearing apart from the coil (see photos below) and I’ll be doing the same thing on my Winnie in due course.  If you’re careful digging out the old guts you can just solder the new module onto the back of the stock wiring socket which makes it plug and play.

The advantages are significant for reasons mainly based around the HEI module having current modulation instead of being just a big switch (like the Mopar ones are).  So it powers up the coil only until the coil is saturated, then it pulls back on the current.  That way it doesn't need a ballast resistor to avoid overheating itself or the coil and without a resistor the coil can charge to higher voltage and faster.  Also the risk of ballast failure is eliminated (obviously).

In theory you can run any coil with it and any coil you put on there will run at it's optimum but a low impedence coil makes best use of the system and can deliver 50 + kv at the plug.

I already had a low impedance Accel coil, but I’ve also tried an “E-core” coil listed for a 1996 Mustang (not expensive) which worked very well.  I used a Mallory module but a standard GM unit is cheaper (last time I looked RockAuto had them for a few $$).  Anything listed for a late ‘70s GM V8 should be fine.

I can't take all the credit for the idea of hiding it in the box - I saw someone on another forum who had hidden one in a Motorcraft box (the same upgrade works with Ford Duraspark distributors).  I think I may be the first person to hide one in a Mopar box.

The HEI fires the coil on the other side of the impulse slope, so after fitting it you do have to adjust the timing slightly.  Also you need to have the two leads from the distributor the right way round or there’s a slight misfire (I used trial and error on that one).

So anyway see below what I did using an old Mopar box that had given up the ghost (and let’s face it there’s a plentiful supply of those).

PS - I have to post the pics below as I'm having trouble putting them in the same frame as the text for some reason

[UK-Winnie]

[UK-Winnie]

As a further PS - the module is mounted against the front of the box to make use of the heat-sink.

I can find a wiring diagram if anyone's interested.  Or just Google "mopar HEI conversion" or something like that and you'll probably find one.

Total cost can be around $25 (less than a new Mopar box I think).

Forgive me if this mod. has been posted before but I can't see that it has.

[Stripe]

Hmm, Interesting.  First I've seen it here.  Thanks for that info..

[DaveVA78Chieftain]

The HEI conversion is normally associated with it built into a replacement distributor so all the external parts are eliminated except for the coil.

http://www.ebay.com/sch/i.html?_sacat=0&_from=R40&_nkw=mopar+hei+distributor&_nkwusc=mopar+hei+distribtor&_rdc=1

Dave

[ClydesdaleKevin]

Just remember though...if the SHTF, an old fashioned points system will keep on running after an EMP, and the HEI stuff will fry...lol!

Kev

[UK-Winnie]

Actually Dave, in some of those aftermarket ones the coil is also eliminated as they put a new coil inside the distributor cap (GM style), but it makes the cap big and it can get in the way.  Also you don't get to choose your coil.

You can see where the ones without a coil have a bump on the side of the body where the HEI module lives. 

I wouldn't want to put anyone off using one of those but a friend of mine had the Ford version on his 351 Mustang and it didn't last too long and I've heard similar tales so I think the quality on the cheaper ones is probably not that great, but it's definitely an easier option than mine if you don't mind spending the money.

I'll go for my version again because (in order of importance):

1)  the pleasure of knowing I built it myself
2)  it's cheaper
3)  there's more control over the quality of the electronics
4)  it uses the original distributor (including the pick-up coil) which I've always found to be good quality
5)  it's more stock-appearing (slightly)

Kev  - when we emerge blinking into the sickly yellow sunrise of that post-apocalyptic dawn, the first thing I'll be doing is looking for my old points distributor - LOL
Cheers
Steve

[ClydesdaleKevin]

LOL Steve!  Just keep the old stuff as a spare and you'll be right as rain.

Kev