Converting to HEI, need 12v (Ign 12) source

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Conrad

Conrad

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[I have googled for days... just not finding the right thread, or have gotten to dead links. I may answer my own question here as I'm going back out to do more probing.]

I'm converting to HEI (Classic HEI kit) and need a good 12v source for crank (Ign 12) to feed the coil. I may have caused my own problem because I first simplified by removing the old components/connections.

I am using the wire that went to Pin 1 of the ECM for 12v for Run, but then lose 12v when I crank. (This is expected because it comes off Ign 11.) The engine cranks, so I know I am sending voltage through the starter relay. Am I going to need to tap that connection for the 12v Crank source?

I no longer have the ECM, Ballast, and have bypassed the seatbelt safety relay. I have found all the 12v sources for Ign 11 (Run) but am trying to find 12v for Ign 12 (Start). TIA.

Once I get this tackled, then I plan to add a relay to feed the 12v from the battery.
 
you should have had two wires that go to the ballast resistor...brown and blue...if you would connect those two wires together ...with no resistor....that will provide 12 v at start and run..
 
^^The above.

You have a service manual?

Coming out of the bulkhead, ORIGINALLY was a brown wire going to one of the ballast connections. This is IGN2 sometimes called the bypass circuit. It essentially goes to coil+ Find and connect that to your IGN 1 (run) and off you go

ON A SIDE NOTE please check for voltage drop in the IGN 1 (run) circuit which will cause overvoltage from the regulator

Turn the key to "run" engine stopped

Set your meter to low DC volts

Hook one probe to battery + such as starter relay battery stud

Hook the remaining probe to "ignition run"

You are hoping for a very low reading, the lower the better. More than .3V (three tenths of one volt) means you have excessive drop in the harness and connections. One way around it is to use the "run" voltage to key a relay, and feed the ignition, VR, and other underhood loads off the relay.
 
Thanks for the confirmation. I had tried connecting the brown and blue but was not getting 12v on crank. I am not getting voltage from the brown coil+ wire on crank, so I have a problem to track down somewhere.
 
That wire in earlier cars used to be simple..........came off the ign switch, went straight through the bulkhead and to the ballast

In the 74 book I show a splice where it branches off to the under--dash interlock box. Is it possible it got cut there?

I would access the ignition switch connector immediately and check there

Only place I see losing it is at the switch connector

at the branch splice to the interlock

or through the bulkhead connector
 
You could put the coil "Run" power supply on a switch until you get the original stuff figured out, if you wanted to.
 
Thanks for the help. I appreciate it.

The seatbelt interlock relay is located near the Ballast Resistor - and I had already bypassed it by splicing the yellow wires together. The yellow there only gets 12v when ignition is in run however.

So where I am right now is that the engine cranks, I let go of the key so that it backs off to run and the car starts and runs without quitting. Yay - so the HEI conversion is working. So I know I'm not getting 12v to the coil when cranking - and when the ignition is in run the 12v hits the coil and the engine fires.

Theory of operation question - when I'm looking at the wiring diagram, it looks like I only get 12v to the Brown+Coil from the alternator when the engine is cranking. That's what the wiring diagram looks like. Once the engine starts, the Amp gauge is far left and Oil Light is on. The alternator side of the wiring is hacked together from the Previous Owner, so I can't vouch for it.

I could have a bad alternator or voltage regulator - though I replaced the VR recently. I'll check that next. I checked the connections under the dash, so I think I'm ok there - though the wiring there is not perfect by any means.

BTW, I thought the same thing and looked at "cockpit" style switches to make the coil hot before cranking... . That would be cool I have to admit.
 
"Thanks for the confirmation. I had tried connecting the brown and blue but was not getting 12v on crank. I am not getting voltage from the brown coil+ wire on crank, so I have a problem to track down somewhere."

This gave great information, and you do indeed need to find out why this is like Del suggested for the loss of power in the crank position of your ignition.
Otherwise a switch will be required. (you could even think of it as a theft deterrent if you hide the switch) :)

Personally, I'd prefer mine working like it should.
 
It should not take long to track this down, Conrad. We can step you through this. First place to check.......because it's easy to access........is the ignition switch connector coming out of the column
 
here is a 71 Dart...i bet the colors of the harness coming out of the column are the same..,,,,those brown and blue wires again
 

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This is what the ignition switch connector looks like for 73/ 74 You access this near the small trim plate where the column meets the dash. You are interesed in J2-12BR which means arbitrary circuit no. J2, a no 12 size wire, and it's BrowN

Check both sides of the connector. You should have battery voltage there when the key is twisted to "start."

If you do not, check at the bulkhead connector
 

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The bulkhead connector from the 73 manual. THE 73 AND 74 ARE PICTURED REVERSED. Check carefully as I'm not sure how this is oriented. You can tell by carefully examining the "keys" to the individual sections

Your "run" wire, dark blue, should be cavity "N" and your "bypass" J3 (Brown) is cavity Q

You need to check that on both sides of the connector, and "wiggle" the connector under the hood
 

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ALSO CHECK the white plastic "engine" connector. I believe this is the ONLY white plastic connector. It separates the engine from the rest of the car

Terminal 2 is your J3 BROWN circuit feeding the coil
 

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So what have you found? I've outlined where to check
 
I had the same issue, no power to one of the ignition power wires. The bulkhead connectors were loose. A test light was a big help probing the bulkhead and steering column connectors.

I understand what you are attempting to do now. Using a relay, pull power from starter relay lug and tie two current ignition supply wires together for a trigger.

Piece of cake to set up.

Trailbeast, what is the amp pull of the HEI systems?
 
Same issue when I custom-wired the underhood in my 65 Dart. I had ASSumed the IGN1 wire got power in both "run" and "crank" positions (why not, Mother Mopar?). I found the engine would crank and crank with no spark, then sometimes fire as I released the "start" position, exactly opposite the old "fires only when cranking" problem from a broken ballast. Finally figured it out. I just jumpered IGN1 & IGN2 together at the key switch, which you can simply do since you have a good wire to coil+ on IGN1, which is all you need. The wiring schematic doesn't tell you exactly how the key switch works, so only by reading here can you learn such oddities.
 
BillGrissom said:
Same issue when I custom-wired the underhood in my 65 Dart. I had ASSumed the IGN1 wire got power in both "run" and "crank" positions (why not, Mother Mopar?). I found the engine would crank and crank with no spark, then sometimes fire as I released the "start" position, exactly opposite the old "fires only when cranking" problem from a broken ballast. Finally figured it out. I just jumpered IGN1 & IGN2 together at the key switch, which you can simply do since you have a good wire to coil+ on IGN1, which is all you need. The wiring schematic doesn't tell you exactly how the key switch works, so only by reading here can you learn such oddities.
Click to expand...

In most models, the wire that is hot in run position feeds other things that would rob power from start. To see the brake lamp, etc.. light up at ON the go off at START then light again after start is one simple example. Other examples like the charging system get much more complicated.
 
Something that most don't realize... While the switch is in the run position current is present through the ballast resistor, on the blue wire , all the way back to the ign' switch. So even where a ballast resistor isn't required, it and a diode and a relay would put power at the right places at the right instances.
 
crackedback said:
I had the same issue, no power to one of the ignition power wires. The bulkhead connectors were loose. A test light was a big help probing the bulkhead and steering column connectors.

I understand what you are attempting to do now. Using a relay, pull power from starter relay lug and tie two current ignition supply wires together for a trigger.

Piece of cake to set up.

Trailbeast, what is the amp pull of the HEI systems?
Click to expand...

Never actually checked into it for a sure answer on that since they run using the same requirements for wire size as the cars they came on.
I do however stress in the instructions the importance of a good power source for them along with the importance of a good ground for the ECU.



BillGrissom said:
Same issue when I custom-wired the underhood in my 65 Dart. I had ASSumed the IGN1 wire got power in both "run" and "crank" positions (why not, Mother Mopar?). I found the engine would crank and crank with no spark, then sometimes fire as I released the "start" position, exactly opposite the old "fires only when cranking" problem from a broken ballast. Finally figured it out. I just jumpered IGN1 & IGN2 together at the key switch, which you can simply do since you have a good wire to coil+ on IGN1, which is all you need. The wiring schematic doesn't tell you exactly how the key switch works, so only by reading here can you learn such oddities.
Click to expand...

This is the way our instructions suggest to do it.

RedFish said:
In most models, the wire that is hot in run position feeds other things that would rob power from start. To see the brake lamp, etc.. light up at ON the go off at START then light again after start is one simple example. Other examples like the charging system get much more complicated.
Click to expand...

Minor details that no one ever even notices, and the .? amp draw from the starting system is unnoticeable. (especially with a mini starter)
There is also no notable effect on the charging system from tying the Ign 1 and Ign 2 together.
The alternator and regulator operate exactly as they are intended.

I would feel a lot better about it if the problem of why it doesn't currently have spark was answered before the HEI goes in.

Thanks Del, for loading those diagrams and explaining the diag details for him.
 
TrailBeast said:
There is also no notable effect on the charging system from tying the Ign 1 and Ign 2 together.
The alternator and regulator operate exactly as they are intended.
QUOTE]
They'll operate during start which is not as intended.
Contrary to popular belief in this forum, the OEM engineers were not idiots.
But anyway... Just bend the little thingy LOL Good luck to all
Click to expand...
 
RedFish said:
TrailBeast said:
There is also no notable effect on the charging system from tying the Ign 1 and Ign 2 together.
The alternator and regulator operate exactly as they are intended.
QUOTE]
They'll operate during start which is not as intended.
Contrary to popular belief in this forum, the OEM engineers were not idiots.
But anyway... Just bend the little thingy LOL Good luck to all
Click to expand...

No offense meant here, but if we went by that then we would all be running points and condensers, or ballast resistors and ignition switches with two separate ign. poles just so the ignition could have two different voltages so the coil can live through it.
At the time these cars were built it was the best they had under the limitations of cost and availability.
This isn't the case any longer, as we have much better eletronics available today.
It's not a question of thinking OEM engineers being idiots, but just limited to what they had to work with at the time.
Click to expand...
 
RedFish said:
Something that most don't realize... While the switch is in the run position current is present through the ballast resistor, on the blue wire , all the way back to the ign' switch. So even where a ballast resistor isn't required, it and a diode and a relay would put power at the right places at the right instances.
Click to expand...

This is "sort of true" but the fact is there is not enough drain on there to bother

RedFish said:
Contrary to popular belief in this forum, the OEM engineers were not idiots.
Click to expand...

That might or might not be. There's been plenty of idiotic decisions made by automotive engineers and designers over the years, in general. But even if they weren't idiots the 'low buck' design of these electrical systems was borderline. All you need to do to prove that is to do one or two things.........add some accessory such as a two-way radio that would have been "back in the day" and or put a larger alternator on the car.

I've seen plenty of electrical problems in these girls "back then" and I didn't need Al Gore or the internet, either.

ONE of them was my own 70 V code RR in the early seventies
 
Redfish is correct. There is a slight advantage in having the alternator field un-powered while cranking, so it doesn't resist the starter. However, at the low rpm of cranking there would be minimal force. Also, the field actually does get powered via back-flow thru the ballast resistor, and since the ballast is 0.5 ohm vs say 50 ohm for the field, it pretty much gets full power, so "true, but a nit".

Finally, didn't later cars (~1980) drop the ballast resistor and use a "ballasted coil"? In that case, I doubt there was a separate IGN1 or IGN2 anymore. I suspect with electronic ignition, the "bypass ballast while cranking" isn't really needed. However, they might have done that after the smart old engineers retired and the kids and accountants took over.
 
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