need help troubleshooting Duraspark II/GM HEI

[jamyers]

Yes, you'll need to cap/plug the SCV vacuum line, or else you've got a vacuum leak.

 

[FalconSedanDelivery]

the distance to the reluctor and pickup is not adjustable , BUT , I have seen the roll pin that secures the reluctor to the shaft , broken sheared or missing on parts store rebuilds ( why I use them for cores and not as is ) if its sheared or missing it will be out of phase , hense the crazy timing settings mentioned in above posts , check it out , also possible that Vac advance unit is broke ( it locates the breaker plate in relation to the reluctor and can effect phasing as well )

 

[Lazy JW]

....
I have the vacuum hooked to the manifold ....

Unhook the vacuum advance and leave it unhooked until ALL other tuning issues are corrected. Having it hooked up just adds another variable to the mix which further confuses things.
Joe

 

[Caballo Diablo]

Thanks Joe , I took your advise and unhooked the dizzy from vacuum and plugged the vac.

Now I have found out a new piece of info that seems weird but may help get to the root of the issue.

With the vac unhooked, it still idled well, revved well , but still I could not drop it in gear ( C4) without it dying immediately...

But then will sitting there in the garage scratching my head, I turned on the head lights so I could see the panel and radio just cause....and then I could back in and out of the garage with no problem....until I turned off the light/radio. I repeated this several times just to make sure.

Does that mean anything to anyone? I swear I'm not drink'n

--mitch

 

[addo]

Hmm! Check your system voltages.

 

[Caballo Diablo]

Thanks Addo,

Here's what I have..

+ side of the coil, with the switch on, car not running = 12.5
- side of the coil, with the switch on, car not running = 12.5

+ side of the coil, with the switch on, with car running = 9.0
- side of the coil, with the switch on, with car running = 4.5-5.0

..but I don't know what they should be...

Also the voltages coming from the orange and purple wire on the dizzy both show about 4.5-5.0

What other voltages should I check? I think I am going to run a temporary test wire straight from the battery + to the coil + to help isolate a possible voltage issue...other ideas?

Thanks

Mitch

 

[Caballo Diablo]

Well I hate to jump the gun again...but I hotwired the coil and now it seems to be working, I can shift into gear, go forward and backward without it dying. So I guess the problem is maybe the "ballast resistor" So I should be able to bypass that.. Hopefully tomorrow I can get it all buttoned back up and give it a real test, on the ROAD! ( but not too far from home the first time )

Thanks again for everyone's suggestions,

--mitch

 

[jamyers]

Thanks Addo,

Here's what I have..

+ side of the coil, with the switch on, car not running = 12.5
- side of the coil, with the switch on, car not running = 12.5

+ side of the coil, with the switch on, with car running = 9.0
- side of the coil, with the switch on, with car running = 4.5-5.0

..but I don't know what they should be...

Also the voltages coming from the orange and purple wire on the dizzy both show about 4.5-5.0

What other voltages should I check? I think I am going to run a temporary test wire straight from the battery + to the coil + to help isolate a possible voltage issue...other ideas?

Thanks

Mitch

Something's not right there, the HEI module and DS dizzy both want full 12+ volts continuous. I'm not sure why yours varies with the engine running. Is your HEI module *well* grounded? It grounds through it's mounting screws, some folks add a ground strap for insurance.

Like you said, it's easy enough to hotwire from the battery straight to the coil/HEI module to check things.

I'm not positive, but I think your Mustang has a resistor wire instead of a ballast resistor. On my '62 Ranchero, it was the wire between the ignition switch and the firewall connector (the wire from the firewall to the coil is standard wire). Bypass/replace that resistor wire, and you'll have full voltage to the ignition.

Make sure it's wired like this:

 

[addo]

It all sounds about right to me.

The charging voltage with headlights on would be interesting to know, as the apparently changed load affected ignition behaviour.

 

[fordconvert]

In theory ballast resistor should get removed. I used a relay to bypass mine and just for fun I removed the relay to see what would happen if it did run off the resistor. It didnt seem to change anything at idle or a quick trip around the block. I put it back but at least with my setup it didnt seem to hurt anything. My running at idle voltage is around 14.7 after a cold start with headlights on. It will drop down around 13.5 at times but never seems to get lower. I am running a large optima red top battery (I think its around 1000cca).

 

[mach1 mark]

I put in a DUI a few months ago and you have to have a 12 volt connect. The easiest way I found is connect from under the dash. The coil for you old system only requires 6 volts so you have to run a wire to the connector behind the dash.\

Unloosen the the screws that hold the gages to the dash, reach behind the gages and unscrew the speedometer cable. This should only be hand tight. (You may have to take the two screws out of the hand brake handle bracket to get your hand behind the dash to get to the speedo cable)\

Once this is done your gages should pull out slightly to look behind the dash. You are looking for a PINK wire that runs from the ignition Key switch, to a male-female connector. (that wire is red) Pull the pink wire out of the connector. replace with new wire on the same type of connector into the female connector that the pink wire one came out of. Run this new wire through the firewall and connect to the blaster. You can wrap the old wire (both ends) with electrical tape and let it dangle. This should give you 12 volts when the switch is on, and will cut off when switch is off.

I hope this helps.

 

[Caballo Diablo]

Mark,

That is pretty much what I did this morning. I then took it out for a drive, first around the neighborhood, followed by a ~10 mile loop to get gas. I am very happy with the results, still a little tweaking to do, it was pinging a little under load so I still need to tweak the timing and it stalled a 3-4 times at idle in drive, but started back easily, so I'm almost there.

Thanks

--mitch

 

[mach1 mark]

Good to hear it!!