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Author Topic: Converting Duraspark Module to GM HEI  (Read 4993 times)

lonesouth

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Converting Duraspark Module to GM HEI
« on: February 04, 2014, 01:14:54 PM »
Parallel thread and discussion here: http://classicbroncos.com/forums/showthread.php?t=237108

I'm going to make the change, here's the schematics.  Main reason for swapping is that I fried two duraspark modules on saturday and it shouldn't be much work to move some wires since I will already be digging in to see what's wrong.  I'm planning to mount the e-coil and module(with heat sink) on the power steering bracket behind the reservoir.





« Last Edit: February 04, 2014, 04:58:24 PM by lonesouth »
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

JustaFordGuy

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Re: Converting Duraspark Module to GM HEI
« Reply #1 on: February 04, 2014, 02:39:46 PM »
A lot of people will mount them in an old Duraspark module housing and use the factory wiring because it makes a good heatsink and you can use a factory module in a pinch.

I still think we should test your current module because I think something else is wrong.
77 Bronco, 302, 4bbl, Hei, C4, PS, PB, BCB-A/C, 33" KM2s, D44/Lock-Right Chromo axles, 9"/Grizzly locker, 2.5" sl, 1" bl, Bilstein shocks, 1 ton steering, JB-fab twin stick, D20,

2017 F350 CCLB KR FX4
2005 F250 CCSB Lariat FX4

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #2 on: February 04, 2014, 03:03:28 PM »
Feel free to pick it up on your way home after work.  Bronco is sitting in the front yard, old module is behind the back seat.  I'll be home at 6, but have someone coming to look at the car tonight at 6:15. 

I may just take it, the duraspark module, down to autozone.  I read on CB that they may have a tester.
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

JustaFordGuy

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Re: Converting Duraspark Module to GM HEI
« Reply #3 on: February 04, 2014, 04:50:53 PM »
Can't come by tonight.

Good idea about the tester.
77 Bronco, 302, 4bbl, Hei, C4, PS, PB, BCB-A/C, 33" KM2s, D44/Lock-Right Chromo axles, 9"/Grizzly locker, 2.5" sl, 1" bl, Bilstein shocks, 1 ton steering, JB-fab twin stick, D20,

2017 F350 CCLB KR FX4
2005 F250 CCSB Lariat FX4

FloridaBronco

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Re: Converting Duraspark Module to GM HEI
« Reply #4 on: February 11, 2014, 04:23:31 PM »
got rid of the duraspark stuff on the 79 and it was more powerful and quicker starting. I just got the Summit racing billet drop in HEi (chevy) distributor. Simple few wires and easy pezy.

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #5 on: February 12, 2014, 09:27:26 AM »
did a little poking around, have 12V at B & C, means coil should be good, dizzy is putting out 5VAC, means it should be good.  Going to pick up another HEI module and TFI coil today.  Really, just suspect the HEI right now.
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #6 on: February 12, 2014, 03:01:48 PM »
picked up a new module and coil at lunch.  got to thinking more about it and a couple things could be at play.  I have 12V at the I on the starter solenoid in run, it should be 0.  The I is not the correct place to get power to the coil because it is only hot in start, not run. 

tonight I'm going to remove the tach wire from the circuit and power the module from the battery.  If that doesn't work, I'm going to replace the coil, and then the module.  If it still doesn't work, I'm going to douse it in gasoline and burn it to the ground.
« Last Edit: February 12, 2014, 04:52:08 PM by lonesouth »
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #7 on: February 12, 2014, 10:38:36 PM »
I pulled my setup out of the bronco and tested it on the bench using an old 302 duraspark dizzy.  I was able to get spark on the bench, so I know the module and coil are good.  I'm going to pull my dizzy and see if it still works on the bench.  at this point, i think I have a bad pickup coil
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

FloridaBronco

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Re: Converting Duraspark Module to GM HEI
« Reply #8 on: February 13, 2014, 07:55:11 AM »
picked up a new module and coil at lunch.  got to thinking more about it and a couple things could be at play.  I have 12V at the I on the starter solenoid in run, it should be 0.  The I is not the correct place to get power to the coil because it is only hot in start, not run. 

tonight I'm going to remove the tach wire from the circuit and power the module from the battery.  If that doesn't work, I'm going to replace the coil, and then the module.  If it still doesn't work, I'm going to douse it in gasoline and burn it to the ground.

or you could give it to me. I do think you are over thinking this. for $100 you can get simple set up and no issues again.

JustaFordGuy

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Re: Converting Duraspark Module to GM HEI
« Reply #9 on: February 13, 2014, 09:44:50 AM »
Less than a $100, I already posted a link for a new 1 wire heI dist with plug wires for $60. ;)

You can test the pickup with a volt meter.

You are correct about the I terminal on the solenoid, it should only have power during start. Is the power coming from the wire or the solenoid?
77 Bronco, 302, 4bbl, Hei, C4, PS, PB, BCB-A/C, 33" KM2s, D44/Lock-Right Chromo axles, 9"/Grizzly locker, 2.5" sl, 1" bl, Bilstein shocks, 1 ton steering, JB-fab twin stick, D20,

2017 F350 CCLB KR FX4
2005 F250 CCSB Lariat FX4

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #10 on: February 13, 2014, 02:36:30 PM »
haven't figured that part out yet.  I did get a new duraspark dizzy and pickup at lunch.  I have parts to go back to the store anyway so I figure if it is just the pickup then I'll replace that and if not then I'll have the distributor already.  So it should be running tonight.

don't see where you posted a link to that distributor & plug wires...

Keep in mind that this was originally supposed to be a simple $20 fix and had it been the module that was bad, I would be pretty happy right now.  Given that it has dragged out this long, there is some noise that blurs the outcome and success of the swap.
« Last Edit: February 13, 2014, 02:38:52 PM by lonesouth »
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

JustaFordGuy

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Re: Converting Duraspark Module to GM HEI
« Reply #11 on: February 13, 2014, 03:55:40 PM »
I posted the link in reply to your post in the sowega thread. It is a great deal but there is nothing wrong with duraspark. I would only replace with the Chevy heI style dist if my stock dist was bad.
77 Bronco, 302, 4bbl, Hei, C4, PS, PB, BCB-A/C, 33" KM2s, D44/Lock-Right Chromo axles, 9"/Grizzly locker, 2.5" sl, 1" bl, Bilstein shocks, 1 ton steering, JB-fab twin stick, D20,

2017 F350 CCLB KR FX4
2005 F250 CCSB Lariat FX4

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #12 on: February 13, 2014, 04:12:01 PM »
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #13 on: February 13, 2014, 04:50:53 PM »
I ended up putting the coil and module on the same piece of aluminum and mounting it to the alternator.





« Last Edit: February 14, 2014, 09:08:45 AM by lonesouth »
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

lonesouth

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Re: Converting Duraspark Module to GM HEI
« Reply #14 on: February 14, 2014, 09:08:10 AM »
Man, that was fun /sarcasm.

So it was easy enough to drop in the new distributor and get the spark back, that part only took about 15 minutes.  This one worked, gave spark, but the vacuum advance is bigger and causes even more problems getting it timed/running, so back to the old distributor.  I swapped the pickup coil on the old distributor.  I should have done this first, it took about 5 minutes to do and could have easily been done on the engine. 

So, now I have my old distributor with a new pickup, which I fail to stab correctly.  No biggie, I think, I'll just find TDC and put it in how it is supposed to go.  DISCLAIMER: Just because it is on the internet doesn't mean it is true.  I spent 30 minutes resetting the firing order based on a printout that said 351W...Yup, it was a 302 firing order.  I grabbed my Chilton manual and like to smack myself in the head with a hammer.  Now I have the right firing order, stab the distributor again, rerun the plug wires and nothing.  180* out.  Rerun again, and I can only get it to limp along with the throttle at 3/4.  Restab again, 3 more times, till I get the shaft advanced one tooth so I can finally get the distributor in the sweet spot that allows it to run. 

But wait, NO, there is electrical wiring to contend with too.  The I terminal on the starter solenoid is not hot in run.  See this discussion.  I ultimately used the green/red stripe that used to run to the voltage regulator, but now runs to my 4g alternator and electric choke, as the 12v source for my HEI module.  But let me tell you, when it is 35* outside, and you've already been fighting the darn thing for two hours, your mind isn't as sharp as it needs to be.  So, I hooked my 12v to the Coil -, leaving the Coil + and HEI open.  Interestingly, you will still get a spark, it just won't come when you need it. 

30 more minutes of head scratching and rerunning plug wires, and I finally find the 12v hooked up wrong.  Move the 12v to the right place, flip the key, and the engine rumbled to life.  At this point, I hadn't even bothered putting the distributor retainer back in, shut it down, reinstalled the retainer, fired up, timed, and it is now purring right along.  There is an occasional miss, but I'm going to chalk that up to my plugs and wires, which are shot.  I even managed to rip most of the plug boot off the #2 wire when I was pulling that plug to find TDC on what I thought was the #1 plug.  I also need to add a relay and 10-12ga wire for the 12v.

Final Thoughts:
----------------

This really is a simple upgrade, or lateral move depending on which camp you're in.  The hookup is stupid simple, and the function is nearly idiot proof.  If you have a good, RUNNING, ignition system to begin with, this shouldn't take more than an hour to do.  Most of my time was spent diagnosing the problem, and ultimately throwing parts at it till I found the problem.  The complexity for me is compounded by having to set the distributor forward a tooth.  That's not really a big problem, but not having a lot of experience, before now, setting a distributor, running plug wires and setting timing, there was a learning curve for me to tackle.

At the end of the day, I think I'll be happier with this setup.  I get simpler wiring, easier to access parts and a hotter spark.  Best of all, all of it is off the shelf and I can find it at any parts store, and it is cheaper to replace than duraspark should it go bad.



Experience is knowledge, gained immediately after you need it.
1977 Bronco U15 ,351w,C4,PS,PB,1"BL,32s

 

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