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I tried HEI with GM module and GM alternator, but with MSD6
https://slantsix.org/forum/viewtopic.php?t=27070		 Page 1 of 1
Author:  rock [ Fri Feb 08, 2008 1:11 pm ]
Post subject:  I tried HEI with GM module and GM alternator, but with MSD6
Fellow ignition lovers,

Once again, having something that works great, I want to try something else. This time I want to use an MSD6 or MSD6A and Blaster 2 coil with my Mopar electronic dizzy and GM alternator. Note I don't include my GM HEI module in this mix. And, therein is my question. It seems to me the diagram on page 19 of MSD's online manual for MSD6 series modules that use a Chrylser electronic distibutor AND MSD module means NO GM module is needed....am I correct?

I ask because I just figured out the wiring for my Mopar electronic dizzy to GM module to GM two wire alternator and things work great.... and if I don't need the GM HEI module for my desired change to MSD, then I will disconnect the GM HEI module and leave it in place for "just in case". (I ran two complete wiring systems , one for the Pertronix and one for HEI with a Mopar dizzy, just to have redundancy in case the HEI system failed I could pop the Pertronix back in.)

As background, my vehicle is a '64 and has no fusebox. It seems to be in between '64 and '65 because the wiring diagrams for both these years have wiring segments that I needed to use to do all my rewiring. Wiring in a GM alternator to thet GM HEI module is a twist on what is usually asked on this forum, because most people seem to be using the Mopar alternator. Thinking beyond "just put the wires together from the resistor" was needed to a GM alternator was needed, because every resource I have used only talks about wiring to the ignition switch...and on Mopar switches there are THREE hot positions, one always hot, one only hot on starting, and ACC, which is also hot at run.

Seeing how the switch works makes me u nderstand where current is in each position when the resistor is bridged, no FLD is connected on Mopar, and and an internal regulator has to be turned on and blocked for charging with a diode.

The point is not about how great I am, but rather the considerations once you move to multiple ignition changes are more complex than those for HEI alone. It seems to me that MSD has got it figured out how to do our ignition switches, NO resistor, and feed a GM alternator with NO GM HEI module...am I right? Has anyone done this on there machine?

Thanks
rock
'64d100
Author:  SlantSixDan [ Fri Feb 08, 2008 1:37 pm ]
Post subject:  Re: I tried HEI with GM module and GM alternator, but with M
Quote:
I want to use an MSD6 or MSD6A and Blaster 2 coil with my Mopar electronic dizzy and GM alternator. Note I don't include my GM HEI module in this mix.
Correct...either you use the MSD box or the HEI module. Not both at the same time.

Quote:
I ask because I just figured out the wiring for my Mopar electronic dizzy to GM module to GM two wire alternator and things work great...
Good reason to leave it be...! B-) Seriously, you likely won't notice any difference at all between HEI and MSD.
Quote:
I will disconnect the GM HEI module and leave it in place for "just in case".
That is exactly what I did on my '65. I put HEI on it, it ran great, and I managed to convince myself that MSD just had to be better, so I put an MSD box on the other inner fender, but left the HEI module in place. Found no difference (benefit or drawback) with the MSD, but when the MSD box came up lame one day in a rainstorm, it surely was nice to be able to plug the HEI back in and get going.
Quote:
the resistor is bridged, no FLD is connected on Mopar, and and an internal regulator has to be turned on and blocked for charging with a diode.
Remind me again how much "simpler" the GM alternator wireup is? :lol:
(just yanking your chain)
Author:  Aggressive Ted [ Fri Feb 08, 2008 3:40 pm ]
Post subject: 
Thanks Dan! :D

That is good to know that the HEI is just as good and it is allot cheaper to carry a spare HEI module in the glove box instead of another MSD box.
Author:  Jopapa [ Fri Feb 08, 2008 4:11 pm ]
Post subject: 
Quote:
Thanks Dan! :D

That is good to know that the HEI is just as good and it is allot cheaper to carry a spare HEI module in the glove box instead of another MSD box.
Seconded. I was throwing around the idea of plunking down the $320 for an MSD Digital 6 when I return home, but hearing that the HEI is just as good makes me happy with what I got.

Though the Digital 6 is a multi spark system and that piques my curiosity (but not $320 worth in curiosity)...
Author:  rock [ Fri Feb 08, 2008 4:56 pm ]
Post subject:  Thanks a millon, Dan!
Yep,
Thanks again Dan! What great answers to the main points I was after! how bout that...once again Dan't been where some of us want to explore...what a great forum.

I think I will slide a MSD in because I have one, but put it as a redundant system that can quickly be connected. Who'd a thunk it...HEI equal to MSD!

Thank you, Thank you!
rock
'64d100
Author:  Matt Cramer [ Fri Feb 08, 2008 5:30 pm ]
Post subject: 
I wouldn't say that a HEI module is actually more powerful than a MSD box, but it is likely that the MSD box wouldn't make more power on a typical street slant A hot ignition is more important when your engine is revving so high the coil doesn't have time to charge, or you're making so much cylinder pressure that it blows out the spark if your ignition is inadequate.

Right now my Dart looks to be on track to be complete by this spring - I've set a personal goal to have it ready for the Megasquirt Meet in April. Once it's running, I'm going to use it for a little ignition dyno shoot out to see if I can find any difference between a HEI module, a distributor triggered MSD-6, a crank triggered MSD-6, and some other ignition hardware I've picked up here and there - a set of LS1 coils, the coil pack off a Dodge Intrepid, and a couple of other bits of hardware. I'll be sure to post the results.
Author:  MenkeMoose [ Fri Feb 08, 2008 5:35 pm ]
Post subject: 
I have the MSD 6a, but mostly because I was using it before I learned of the HEI swap. I have also had an MSD box fail in the past. I think the current replacement cost is about $190 for a new one, and you can't buy one just anywhere along the road. You can buy a new HEI module at any parts house, and they're fairly available at junkyards. I now have an HEI module wired up as a spare, so I can slap it in if my MSD fails again.

IMHO, the only reason to spend the extra money on the MSD box would be if you want to use other MSD components such as the timing computer, rev limiters, etc.

-Moose
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