Duraspark conversion KISS Keep It Simple Stangers - Vintage Mustang Forums

Thread Tools
post #1 of 9 (permalink) Old 05-13-2008, 12:06 PM Thread Starter
Senior Member
Join Date: Jun 2005
Location: Kalispell, MT
Posts: 316
Yesterday I spent about an hour helping my dad switch from points to duraspark on his 72 ford with a 351W. I had done the swap before on my 62 Galaxie but before I did the swap this time I did a bit of research because I new there were lots of opinions on how to make the swap. What I found was a lot of people disagreeing as to what the best way to do it was. I had MustangSteve's original drawing from his web page where the white and read get spliced in to the brown (that is how my Galaxie is hooked up) and I had Steve's new drawing which involves running a new wire from the ignition switch to the box and coil to by pas the resistance wire, for a full 12 volts, as well as a couple of others that use relays. All in all the old ways and the new ways are the "hard" way (not that running a few wires, or hooking up a relay is that hard) my dad has an MSD 6A box on his truck and so all I did was hook the magnetic pickups from the MSD to two of the wirs coming out of the distributor and then the original + from the coil went to the red wire on the MSD box, the output wires from the MSD box went to coil and of course power from the MSD box to the battery . That was it, it was done. Took about 10 minutes to hook up including soldering an original Ford plug that plugs in to the distributor to the green and vilote wire supplied by MSD (if you really want it to be simple MSD sells this pigtail ready made) and the rest of the hour was timing, tuning and BSing An way the MSD box has a cranking voltage range of 9-18V and a run voltage range of 5-18V sooooo you can remove the pink wire, you can use the pink wire, it really doesn't matter and eliminates all the extra wires needed to supply a full 12 volts to the ignition box. Of course the MSD box is around $150.00 but the "good" stock ignition control module was $60.00 so almost half and the benefits of the 6A box are more than worth the extra $90.00 spent. Any way thought I would post because in my research I read lots of questions/views about the duraspark swap especially in relation to the resistance wire and that you should or should not bypass it and since a lot of people will be running the MSD box anyway this sure makes things simple and takes out all the questions/options/opinions/headaches.

If it aint broke..... modify it anyway! ! ! ! www.IRSuspension.com

Free Mustang tech info @ www.DazeCars.com
Galaxie and Full Size Ford forum [color:blue]www.Galaxieforum.com
DazeCars is offline  
Sponsored Links
post #2 of 9 (permalink) Old 05-13-2008, 12:17 PM
Senior Member
MustangChuck's Avatar
Join Date: May 2007
Location: Panama City, FL
Posts: 987
Many thanks!!

Check out Popular Hot Rodding, Aug 2009, Pg 35, upper right corner!

My budget makes a shoe-string budget look like Warren Buffett's personal checking account.

1969 Mustang Fastback (work in progress)
(Pics Gallery) (Video)
1995 Mustang GT Convertible (daily driver)
1994 Mustang GT Coupe (donor car)
MustangChuck is offline  
post #3 of 9 (permalink) Old 05-13-2008, 01:24 PM
Senior Member
Crash's Avatar
Join Date: Jan 2004
Location: East Texas
Posts: 1,838
I'll be running an MSD box and Duraspark distributor in my new 408 stroker. I have been wondering how I was going to handle the factory resistor wire.

I'll file this away for future reference. Thanks.

Formerly known as Bashed68.
Resto-modded '68 convertible.
Crash is offline  
post #4 of 9 (permalink) Old 05-13-2008, 04:14 PM
Senior Member
grocery getter's Avatar
Join Date: Oct 2006
Location: sacramento
Posts: 207
that's pretty much the way I did it. I did run the hot wire from the battery to the box. I read it uses about 1 amp per 1000 rpm.

i'm running a six and dist. options are limited.
one of the best and easiest upgrades. I just touch the key and it starts.

grocery getter is offline  
post #5 of 9 (permalink) Old 05-13-2008, 07:59 PM
Senior Member
frdnut's Avatar
Join Date: Dec 2007
Location: Ontario ,Canada
Posts: 3,943
I used the + coil wire to the MSD box as well...As I understand it it is just a trigger wire and doesn't supply the actual voltage to the box..It has seperate red and black wires that go to the battery for that..

68 J code sprint, 408W
11.47@123.35mph in street trim.
frdnut is offline  
post #6 of 9 (permalink) Old 05-13-2008, 10:56 PM
Just some guy
GypsyR's Avatar
Join Date: Jun 2001
Location: SC foothills, USA
Posts: 15,387
I never quite understood the "Duraspark wiring argument". When I first figured out how to retrofit a Duraspark (pretty much pre-internet) I just studied the factory diagrams for a Duraspark car in comparison to my points car. Anybody else can do the same, it's fairly straightforward.
What I have seen on Duraspark car diagrams is that the red wire from the box goes to 12 volts off the ignition switch when the switch is in the run position. The coil wire also comes from the ignition switch run position but passes through a resistor that drops the voltage. There is also a bypass that allows full ignition switch voltage to the coil when cranking the car. Direct from the "crank" position on the switch and tied into the coil wire just after the resistor. Our older points ignition cars had the full voltage to the coil bypass coming from the "I" small connector post on the starter solenoid. Which is about the only place on the car to get full battery voltage when cranking. Everybody has surely noticed how ALL electrical accessories dim when you are starting the car? That's voltage drop to everything else because of all the amps the starter is draeing. With a Duraspark ignition the white wire to the box connects to that same "I" post.
The white wire's purpose IS debatable though. Some say it provides full voltage to the box when cranking (like the points cars did for the coil) others say it signals the box to retard the ignition timing to ease engine starting. Personally I don't see why it couldn't be providing both functions, electrical design engineers tend to be pretty smart.
The resistor wire I have never really understood that well. It's a 12 volt car, so why aren't the friggin coils 12 volts? Older OEM and replacement coils aren't. They can take full battery voltage for short periods such as starting the car, but in the long term they tend to overheat and fail in a variety of ways. People keep finding this out the hard way, over and over. That's reality, regardless of what I think about it. If MSD says use THIS or that coil specifically works and that you don't need a ballast resistor or resistor at all, then well and good. The folks at MSD do indeed have a clue. If in doubt, and you are not using MSD's stuff, then it's a pretty safe bet a resistor of some kind should be used with your coil. Most folks will want to use some way to bypass the resistor for starting in cold weather. "Summer cars" seem to do OK without a bypass.

.... it wouldn't be the first time reality took theory and conjecture out behind the woodshed and gave them a good thrashing.
GypsyR is offline  
post #7 of 9 (permalink) Old 05-15-2008, 12:58 PM
Senior Member
mavken's Avatar
Join Date: Mar 2007
Location: Western North Carolina
Posts: 244
I'm wondering about the merits of the MSD vs Duraspark. The MSD is obviously more powerful, no? If that is so, then the only advantages the Duraspark box would have would be a little less cost and MAYBE retarding the spark when cranking. Retarding would probably help if you are running high compression or maybe if you have some trouble starting when hot (although hot starting difficulty is probably due to other issues). Anyway, if the MSD box is run, why even bother with a Duraspark distrubutor. Wouldn't be just as easy to drop in a points to electronic conversion kit if the distributor is in good shape? I'm planning an upgrade from points myself so I am very interested in this.

Kenny B.
1970 Mustang Sportsroof, Metallic Gold, Ginger interior

"Try not to become a man of success, but rather try to become a man of value" Albert Einstein
mavken is offline  
post #8 of 9 (permalink) Old 05-15-2008, 10:42 PM
Just some guy
GypsyR's Avatar
Join Date: Jun 2001
Location: SC foothills, USA
Posts: 15,387
Durasparks are well proven by literally over a million Fords that left the factory with them. For your basic electronic ignition, they work fine. And if we stop fooling ourselves, provide all the ignition most of us will ever need. The distributors are tunable, Summit sells lighter advance weight springs, there's a website about tailoring the advance curve simply by swapping around the advance weights, and you can even get adjustable vacuum advance cans. A nice plus is that Duraspark replacement parts on the shelves of about any parts store you care to visit. They get along just fine with hi-po ignition coils.
There are some downsides. Used distributors tend to have worn bushings and the advance weights tend to seize because no one ever lubes them (they do have provision for this). And of course they've been out of production for quite some time. Rebuilt distributors are readily available though. Many folks think the Duraspark distributors are too large and unattractive. New control boxes are widely available, the cheaper ones have a bad reputation though. It's sometimes said to be best to buy them two at a time so to have a backup.
MSD boxes ARE better. They provide multiple sparks at low rpm's and stronger spark at higher rpms. There are options like boost retard for turbo cars and other stuff a Duraspark isn't capable of. They have also been know to fail, racers usually keep a spare, the majority of folks have good luck with them though.
MSD distributors are: brand new, made for high performance duty, nice looking, built of better materials and to a higher quality level.
Most MSD boxes get along just fine with a Duraspark distributor when you buy the inexpensive adapter.

.... it wouldn't be the first time reality took theory and conjecture out behind the woodshed and gave them a good thrashing.
GypsyR is offline  
post #9 of 9 (permalink) Old 05-17-2008, 12:20 PM Thread Starter
Senior Member
Join Date: Jun 2005
Location: Kalispell, MT
Posts: 316
I should have clarified a little better. Duraspark is a really good way to go from points to EI. My point was more that there are 3 or 4 different ways to make the swap and different opinions as to which way to swap it out is better. for those that will be running an MSD any way, than why not keep it simple and bypass the module all together. Ironically both of the duraspark vehicles I have have MSD and still use the Module because that is how I hooked them up. I just made this post for those making the swap to make it simple. When I helped my dad I was looking for simple and simple is what we got In the future I will be swaping out the points on my Mustang, and when I do I will do it the module free way even though I have an extra module.

If it aint broke..... modify it anyway! ! ! ! www.IRSuspension.com

Free Mustang tech info @ www.DazeCars.com
Galaxie and Full Size Ford forum [color:blue]www.Galaxieforum.com
DazeCars is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Vintage Mustang Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

For the best viewing experience please update your browser to Google Chrome