I was told that converting a 351 W distributor to a MSD GM HEI dist. would inprove my performance over the Ford dist. I have seen 351w and 351 clevelands at the track with the Ford dist. modified to a HEI. Has anyone ever done this ?? Was it a lot better ?? If you have the plans for converting one over and it helps. Please e-mail me and let me know how. Or who can do it. Seems like it should not be that hard. One other question. Has anyone ever compaired the 351 C Australian heads to the Ford GT-40 heads or any alum. performance heads ??? THANKS !!!

 

It depends on what kind of distributor you have now, and how your engine is built as to whether the MSD would help. If you have points, the new dist would improve performance. If you have ford electronic and are not turning much over 6000, I wouldn't waste my time with the MSD. If I were going to an MSD, it would not be a HEI type. It would be a magnetic trigger and whichever box fits your needs best.

 

If you have an efi engine and using the stock tfi ignition system then I would say leave it alone, its pretty good.

If you currently have the duraspark II set up then I can let you know what I did to make a hei setup with a duraspark distributor. Take a duraspark II distributor for your engine cubic inches, get your hands on a tfi coil (I believe all efi coils are the same but I asked specifically for a 1993 351w f-150 coil, $20 new), and get or ask for a 4 pin module out of a 78 camaro with a 350, $15 new. You will be bypassing the stock duraspark module. The below graphic will show you how, the hei module holds a spark longer than the duraspark module, and I did experience better cold starts, keep in mind its important the gm module stay as cool as possible so mounting it to a heat sink is improtant, and no big deal. You can pic up distributors on ebay for $150-200 that have the large gm coil on top of the distributor, but the tfi distributor is actually better and the conversion below, cost me $40 for all new parts (coil and module) and wiring, distributor not included (I already had that). If sourced from a junkyard its much cheaper, ask around somone might give you these parts. Later

 

JW towards the end of your post you say "the tfi distributor is actually better". Can you do the conversion with a TFI or do I need a duraspark2? My TFI setup is ok, but I would prefer a vacuum/mechanical advance system that the TFI doesn't have......

 

You can't believe everything I write.......just kidding. That was a mistake on my part it should have said tfi coil, not distributor.

You could run a tfi distributor, tfi coil, and tfi module on your carb setup but it would require an aftermarket timing computer (not cost effective unless you have the other stuff already, IMO)... or so that is my understanding.

Yeah use the duraspark II distributor its fine, especially if mechanical and vacuum advance adjustment is something your interested in. Sorry about the mix up. Later

 

Yes, that's what I thought.......I'm planning on getting rid of the TFI when I have a little time......thinking of several other mods as well......I was hoping you had figured out how to do something useful with a TFI for cheap......oh well, the duraspark II is cheap enough......

 

Check around the duraspark II distributor at a junkyard shouldn't cost much at all, then again suppose it depends on who you ask.

I picked up my reman duraspark II distributor two years ago for $70, I don't recommend it but you could probably stick your distributor back in the box and use it as a core...........again I don't recommend it but......

 

jwtaylor

Interesting post on using the GM module. Some questions: Am I breaking some kind of rule by asking the following questions on this thread? I am new to this site and don't want to offend. 1. What can be used for a "good heat sink" ? 2. How do you connect to the GM module, are special terminals needed? 3. What improvements did you notice over the stock Duraspark? 4. I am using a Jacobs variable core coil on my Duraspark, would it work with the GM module? I have read that using a Mopar module instead of a Duraspark box makes a "better" ignition system. I have asked around and no one seems to know what "better" means. Thanks for any resppnse to all these questions.

 

1. I tore apart an old factory radio and took the heat sink out of that, you can go to your local radio shack and ask for computer heats sinks, only a couple of dollars.

2. I used 1/4" female quick connects to connect the wire to the module. I spliced into the wires off the distributor and used a butt connector and shrink wrap.

3. In my experience my cold starts improved greatly, like night and day. I have not kept track of mpg improvements.

4. As long as the coil does not specifically say "for cd ignitions only" then it will work, if in doubt contact summit or jegs tech or jacobs.

I have read similar articles and when the question you asked cam up, the hei was considered better for a few reasons over the mopar module, I can't remember the specifics other but I chose the hei route. I think there may have been compatibility issues, again been a while not sure.

What the hei does that is better than the duraspark is it creates a longer and hotter spark.

Important to bypass the ballast resistor or you won't get full spark.

 

Jwtaylor
Thanks for the feedback. This modification looks like a cost effective improvement. Glad you mentioned bypassing the ballast resistor. I have some extra Duraspark connectors from some past junkyard trips. I think a plug-in harness can be made so you don't have to cut into the original wiring. I heard that the GM ignition produced so much spark that they "ate" rotors and caps. Something to check after a while. Also, I guess that the spark plug gaps could be opened up to GM specs with the hotter spark. Something else to play with.

Thanks again for the time and info.

 

If you do give it a shot let us know what you think. I read somewhere that someone went to a junkyard and picked up everything needed including wiring and distributor for $40, so it can be real cost effective IMO. Good luck