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Jan 21, 2014 | 04:06 PM

irydasteelhorse

Thread Starter

Tuned

Joined: Nov 2012

Posts: 253

Likes: 51

From: billings mt

duraspark

so i have a question for all of you.......does the duraspark box in any way advance or retard the timing?
my box has been dying but besides the usual just dieing, anything under load or up hill and itd ping like a son-ofa-gun. if i unhooked the vac advance, i was fine. timing is spot on. weights are free and springs are good. (i do have a leaking brake booster)
i did get a new box, Echlin, from reading posts here, and guess what?......no spark right outta the box. so even a good name one can be bad ( and test good on napas tester)
thanks for any and all answers, just trying to get this thing ready for summer camping season.

Jan 21, 2014 | 04:52 PM

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

Quote:

Originally Posted by irydasteelhorse

so i have a question for all of you.......does the duraspark box in any way advance or retard the timing?

The Duraspark module retards the timing while the engine is cranking. While the engine is actually running, the Duraspark module does not change the timing in any way, only the dwell.

Quote:

Originally Posted by irydasteelhorse

my box has been dying but besides the usual just dieing

What does it mean for your box to be "dying," what is "the usual dying," and how are those two scenarios different? Remember, I'm talking to you over the Internet; I can only understand what you're saying if you use concrete, explicit terminology.

Quote:

Originally Posted by irydasteelhorse

anything under load or up hill and itd ping like a son-ofa-gun. if i unhooked the vac advance, i was fine. timing is spot on. weights are free and springs are good. (i do have a leaking brake booster)

The scenario you describe has nothing to do with the ignition module itself. This is pre-detonation due to over-lean mixture. If your factory vacuum advance is making this happen, that means your EGR valve is non-operable. Either it's stuck shut, the PVS is stuck shut, or a previous owner removed the EGR valve to "clean up all that smog junk," but look what has happened. Engines that are equipped with EGR are jetted and curved to expect the combustion chemistry inherent to EGR. If the EGR valve is gone, the engine has to be re-tuned. It's much simpler to just keep the factory EGR setup.

Jan 21, 2014 | 06:27 PM

irydasteelhorse

Thread Starter

Tuned

Joined: Nov 2012

Posts: 253

Likes: 51

From: billings mt

the "usual dying" is what ive experienced in the past on a 76 truck, and what ive read about on here that others experience.....itll just die sometimes, like you turned the key off. it restarts almost instantly, but over time it takes longer to start. as the box cools down, itll start again. i dont really know how to explain whats going on with the ping.....i get a buck or hesitation, the more i work it, the heavier the load, the more it does it. not sure if its a fart out the carb or exhaust, . unhooking the vac advance seems to take care of the ping itself, but i havent had a chance to test it yet if that solves the bucking. there is no egr. motor is a strong running 390 of unknown origin.i haul a 10 ft camper and a trailer with atv's in the summer, and i dont want to fight this thing up the mountain loaded like that.thanks for all the help

Jan 21, 2014 | 07:31 PM

devino246

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Joined: Mar 2011

Posts: 8,501

Likes: 4

From: Lynchburg, VA

Quote:

Originally Posted by irydasteelhorse

there is no egr.

And there's your problem.

Jan 21, 2014 | 07:36 PM

Memphis_Sean

More Turbo

Joined: Jan 2014

Posts: 531

Likes: 1

Question; Duraspark II Conversion: Do I use the Blue DS II Module w/1 or 2 Plugs/whats the difference!?

Jan 21, 2014 | 07:45 PM

devino246

Post Fiend

Joined: Mar 2011

Posts: 8,501

Likes: 4

From: Lynchburg, VA

Quote:

Originally Posted by Sean_Reno

Question; Duraspark II Conversion: Do I use the Blue DS II Module w/1 or 2 Plugs/whats the difference!?

You'll have much better luck being helped if you start your own thread...

Mar 23, 2014 | 07:40 PM

irydasteelhorse

Thread Starter

Tuned

Joined: Nov 2012

Posts: 253

Likes: 51

From: billings mt

UPDATE

so, its been a couple months since i posted this. ive fought with it until today. i had replaced the duraspark box with no improvement. after more problems with the bucking and ping, i replaced the distributor with only slightly better performance. with the vac advance unhooked it ran pretty good but i could still get it to buck if i worked it hard at all.
the culprit......TADA!!!!! weak coil! changed it out, and with a lil retiming, its all gone. what i imagine happening here was that it was weak enought that if dist. was advanced enough it ran decent, until under load. after the new coil, i had to retard the timing quite a bit from where it was, and all is golden now. just thought id give an "ending" to this problem for others that may be having the same symptoms.