need help troubleshooting Duraspark II/GM HEI

[Caballo Diablo]

I think I have read all or at least most of threads regarding the Duraspark conversion, but I still have a problem that I need help with.

First it is a 66 mustang/200cid/C4...it runs fine with the 1101 and LOM.

I bought a new Duraspark II/spark plugs and wires/coil/HEI at O'Reilly's.

I have it running...sort of. At 1000rpm or higher it runs well, sounds smooth, but one hair below 1000rpms and it dies abruptly, or If I put it in gear, it dies abruptly.. What I mean by "dies abruptly" is that is does not stumble and die, it dies like turning off a switch. I have the HEI mounted to a huge aluminum heat sink. I don't have vacuum connected to the dizzy, will do that when I get it to idle somewhere near normal and can put it in gear without it quiting.

Any suggestions on how to troubleshoot/isolate the problem? Don't assume I know anything, I only got this far because of what I have read on these forums.

Thanks,

Mitch

 

[Bort62]

Sounds like your timing is way off...

 

[fordconvert]

Sounds like what I did the first time I hooked up mine. I had the polarity wrong going from the pickup coil to the module. What happens is the coil fires when the points on the stator are 'somewhere' between the points on the coil vs. when the are lined up which is much more precise. Also it tends to fire when the rotor is between contacts. Higher R's must get the weights in so it happens to work sort of. I read and re read all the posts, some are/or were wrong. I got onto my problem by reading stuff on MSD's site. In the picture orange and purple are matched up to orange and purple in the dizzy harness. If that was your problem you may have to change your timing again which could mean re dropping the dizzy or moving the wires because the vacuum can may run into stuff and not let you get the timing you want.

 

[Caballo Diablo]

TJ, I checked my connections, even reversed them to be sure, no real difference, still dies just below 1000 rpms.

I tried a new HEI module with the same results. I pulled and dropped the dizzy back in just to confirm TDC.

If it helps, when running at 1000+ rpms the timing is something like 35-40 degrees BTDC. It wont start/run if I have it in the 0-13 range.

This is may be a dumb question, but I'm new at this...but since it will run at a higher RPM with the timing advanced, and I've tried two HEI modules...whats the likelihood the dizzy is not doing what it is supposed to do under 1000 rpms...or does just the fact that it runs at all indicate that the dizzy is functional?

--mitch

 

[Bort62]

That is too much advance at that low of an RPM.

 

[Caballo Diablo]

Thanks Ian, What should I be looking at the correct it? If I back off the timing , it will not start.

Regards,

Mitch

 

[jamyers]

One nice/bad thing about the 4-pin HEI module, they either work or they don't. You've got spark, and you've confirmed the wiring, so I'll argue that the module is just fine and the trouble is elsewhere like the distributor advance, firing order, etc.

That's way too much timing, especially without the vacuum advance operating. Anywhere between 6 and 16 degrees at 1000rpm ought to be in the ballpark, at an idle of 650 rom you'll want 8-12 degrees of advance without vacuum.

I'd go back and double- or triple-check the basic stuff, like the plug wires (firing order). Also, make sure the distributor mechanical advance moves freely, and the weights aren't sticking.

35-40 degrees is almost to the point of having the next or previous cylinder firing, depending on where the advance is...hmm...

 

[mach1 mark]

I have mine set at 35 to 40 with vacuum, I also have a DUI. When I put it in gear it stumbles and cuts off. I have to put it in neutral and rev up then slam in gear. can't figure it out either.

Maybe try setting the ideal to 800 rpm and timing to about 20 btdc?

 

[Caballo Diablo]

That's without vac. With the old LOM, it idled at 600-650 and had adv set at about 12.

But with the duraspark II, it will not run below 1000rpm, as mentioned in the first post, when it drops one hair below 1000 it just dies. And I can't get it to start at all if the timing is not pushed up to 30+ :-(

 

[jamyers]

I re-read your OP, and edited my first reply above.

Just wondering...you *did* block off the SCV port coming out of the carb, right?

Geez, with the SCV blocked off and no vacuum going to the new dizzy...rules out the carb or vacuum...

Swapping points to duraspark/hei really only means that you've changed the way the coil is fired... So the only things I can think of left are the firing order, the distributor's advance mechanisms, or the...cap and rotor orientation? Or something wierd like a wire inside the dizzy shorting out as the centrifugal advance moves around (but the base plate on a DS doesn't move, does it?)

 

[Caballo Diablo]

James, I have not blocked off the SCV at this point, but I'm not sure that it would be a problem yet since I still just trying to get it to idle correctly at low rpms. ???

I've verified cap orientation, lined up the terminal tower maked "1" with mark in the cap adapter, no joy... I don't know how to troubleshoot the dizzy itself, and I hate to spend another $60 to test another new one. I guess I could jsut take it back and tell them it quit ;-) and try anther one

--mitch

 

[mach1 mark]

Mitch, I'll just throw my non-educated stupidity at this problem. But if you back down the timing the RPM's will also go down, therefor dropping the idle down to where the car won't run. Again just my opinion, the timing is set way to high. I would raise the rpm to about 2000, then back down the timing, then set the rpm again to 2000, then back down the timing (while checking the ideal to air mixture) to get the timing down to about 20 BTDC, then try to set the Ideal at 800 rmp. back and forth to back and forth.

By the way nice plane. Stunt plane? keep it in Rock Hill?

 

[Caballo Diablo]

Thanks Mark, I'll give that a try in the morning and see where it gets me

The plane is a 1965 Alon Aircoupe. Definitely not a stunt plane, no inverted flight and only cruises at about 100mph, but a great little plane to fly and great visibility with the fighter inspired sliding canopy...(wear a hat and bring sun screen). And easily recognizable by it's twin tail feathers, like a B-24

I had it at Rock Hill, but I have it up for sale now at Lancaster Aviation, getting out of that hobby $$$$$.

--mitch

 

[LEROY POLL]

C. DIABLO


.....TRY GOING BACK TO YOUR INSTALLATION AND CHECK HOW CLOSE YOUR PICKUP IS TO THE MAG. IS. THIS, IF TO FAR WAY, WILL NOT FIRE THE TRANISSTORS IN THE HEI. CHECK TO SEE IF IT IS AS CLOSE AS THEY ASK FOR.

.....THE MAG. HAS TO CUT THRU THE PICKUP WITH ENOUGH MAGNETIC LINE TO CREATE THE SIGN LEVEL TO FIRE THE HEI. AT HIGHER SPEEDS IT WILL WORK BUT AS IT SLOWS DOWN NOT ENOUGH MAGNETIC FORCE WILL BE GOING THRU THE PICKUP.

.....THIS IS JUST A GUESS. BUT IF THATS NOT IT.....IT SOUNDS LIKE IT IS SHORTING IN THE DIZZY ADV. ( LOOSING GROUND OR TOUCHING GROUND)

LIVE IN GRACE

LEROY POLL

 

[Bort62]

If you have the scv unplugged, you have a vaccum leak.

 

[LEROY POLL]

C. DIABLO


.....TRY GOING BACK TO YOUR INSTALLATION AND CHECK HOW CLOSE YOUR PICKUP IS TO THE MAG. IS. THIS, IF TO FAR WAY, WILL NOT FIRE THE TRANISSTORS IN THE HEI. CHECK TO SEE IF IT IS AS CLOSE AS THEY ASK FOR.

.....THE MAG. HAS TO CUT THRU THE PICKUP WITH ENOUGH MAGNETIC LINE TO CREATE THE SIGN LEVEL TO FIRE THE HEI. AT HIGHER SPEEDS IT WILL WORK BUT AS IT SLOWS DOWN NOT ENOUGH MAGNETIC FORCE WILL BE GOING THRU THE PICKUP.

.....THIS IS JUST A GUESS. BUT IF THATS NOT IT.....IT SOUNDS LIKE IT IS SHORTING IN THE DIZZY ADV. ( LOOSING GROUND OR TOUCHING GROUND)

LIVE IN GRACE

LEROY POLL

 

[LEROY POLL]

C. DISBLO


.....I JUST REREAD WHAT YOU FIRST SAID AND YOU ARE NOT TO HAVE BUT THE *12 AT IDLE.

.....UNPLUG THE VAC. LINE AND RESET THE TIMING TO *12, TRY TO START THE MOTOR. IT SHOULD IDLE. NOW CHECK THE TIMING. YOU SHOULD HAVE THE *12 YOU STARTED WITH. PUT THE VAC. LINE BACK ON. YOU SHOULD STILL HAVE ABOUT *12 -*14 ADV. IF YOU HAVE MORE, THE CARB IS OPEN TOO MUCH. SET IDLE TO AS LOW AS YOU CAN.

.....AT IDLE THEIR IS TO BE NO VAC. AS SOON AS YOU OPEN THE CARB. YOU JUNP TO THE *40!!! NOW AS THE CARB. OPEN MORE THE VAC. OF MOTOR WILL FALL AND SO WILL THE ADV. TO ABOUT *20.
SO IF YOU HAVE VAC. TO *40 AT IDLE YOUR LINE IS LEAKING MANIFOLD VAC. INTO THE SCV AND ADCANCEING THE DIZZY.

.....JUST TO CHECK...WHEN YOU SET THE TIMING YOU ARE TAKING OFF THE VAC. LINE?? AREN'T YOU?? AND PLUGGING IT??

.....AFTER DOING ALL THIS AND IT STILL WORKS THE SAME CHECK TIMING MARK AND DO THE POST I FIRST WROTE.

.....GOOD LUCK TO YOU...YOU NEED IT TO FIND THIS.

LEROY POLL

 

[mach1 mark]

Leroy, how can you check the VAC, With a vac meter? where do you plug it in. and what should it be at at 1000 rpms, and at 2000 rpm?

Mitch, I took my own advise and tried to lower the timing to about 20 BTDC, It didn't run any better, then I set it at 50 BTDC, not good either. I set it back to 35 with vacuum attached and 1000 rpm. keep in mind I have a DUI. , it still stumbles in drive. I read something that the torque converter is not dis-engaging (if that's a word) causing stumbling at low speed to stop. I also have a C4 w/stock converter. Give it a try and post your results.

Mitch , what do you want for the plane. I haven't seen one of those in years. can you carry two people on a cold day? email me, lets fly, can you spin her?

 

[Caballo Diablo]

Well, I think the problem is resolved. Leroy, you mentioned that I should check mag/pick up distance and such, this is a brand new dizzy and regardless I don't know how to set the internals....so thinking that you were on to something, I ran over to the U-Pull-it and for $18 pulled the duraspark II from a 83 Furtura. I spray it will some parts cleaner to get the worst of the grime off and dropped her in.

It cranked right up and is out there idleing at 700 at 12 degrees BTDC..

Now I need to do something to plug the SCV and clean up my install and take it for a drive.

Thanks everyone for your advise.


--mitch

 

[Caballo Diablo]

Well...I spoke too soon. It will idle at a low RPM and the timing is in the 6-12 range, but as soon as I put in in gear, it quits.

I have the vacuum hooked to the manifold and I have the ported source on the 1101 plugged. I do not yet have the scv plugged, but would that come into play at idle? Would that cause it to die going into gear..I'm pulling my hair out, I was sure that once i dropped in the old dizzy from the u-pull-it and it idled so well, I had solved the problem, but o such luck

--mitch