Ignition wiring help with HEI

[ncrobb]

I have a crate 408" magnum stroker from BluePrint. The car is a 1973 Road Runner. The engine came with an external coil HEI style ignition. Knowing I would not need the ballast resistor or the electronic ignition box I decided to make a new wiring harness and not cut up the factory one. Well, I did, and everything works like it should except getting 12v to the coil. I removed the electronic ignition box and ballast resistor wiring from the circuit that comes out of cavity 23 (Ignition Run) of the bulkhead and now it runs just to the alternator field, voltage regulator and the electric choke. As stated, I removed the ballast resistor, so I ran a wire from cavity 22 (Ignition Start) straight to the coil thinking it would have constant 12v on cranking and run. It does not. So, I built an overlay harness with a relay to power the coil so the HEI would have a good 12v source. I got power from the hot stud on the starter relay and used a wire branching off from the choke as a trigger for the relay. Initially I removed the wire from cavity 22 from the coil but realized I wasn't getting power during the crank/start key position. So I hooked the wire from 22 (Ignition Run) back up to the coil thinking problem solved. Nope, it will hit like its going to start and as soon as you release from the crank position the engine dies. It runs great when I jump from the hot post of the battery solenoid to the positive terminal of the coil. I have checked my relay 25 times. I have seen diagrams and read threads saying to tie the brown cavity 22 (Ignition Start) wire and the blue cavity 23 (Ignition Run) wire together and POOF the coil sees 12v and runs. This is pretty much what I have done. In my case there seems to be enough lag between the start and run position in the key switch to cut the ignition and kill the engine. Any thoughts on how to better wire this or where I can pull a 12v source to trigger the relay that is powered during start and run?

 

[PurpleBeeper]

I'm no HEI expert, but you need to have power from Ignition/Run and Ignition/Start going to your coil....both of them...or you get exactly what you describe

 

[Geoff 2]

Congrats on using the HEI system, the best inductive ign system.

Your ign coil. If it used a bal res originally, the bal res must be used or you risk burning out the coil.

 

[diesel_lv]

Lay your old harness up next to it. Get a cheap ballast resistor and gut the back, solder in a 10ga wire in place of the resistor, then fill it in w silicone. Now, connect your wires to the coil as you would with the original harness.

 

[Geoff 2]

2nd sentence in post #5 is 10000% wrong.
With inductive ign systems, which is what HEI is, the coil being used determines if a BR is reqd.

 

[ncrobb]

The coil is an MSD Blaster 2 8202 which was reccomended by BluePrint. By connecting both the 22 and 23 circuits to the coil positive I have effectively tied the run and start circuits together into the coil. Maybe the lag is in the relay? I’m going to try a jumper from the choke wire (blue run cavity 23) to the coil positive along with the ignition start (brown start cavity 22) to the coil positive. Another thing I’m going to try is using the ignition start wire to also trigger the relay along with the choke wire (ignition run). Maybe both at the relay will work?

 

[wagonman]

IIRC when I did the GM conversion on My 73 Duster I canned the BR and just tied the start and run together. Both wires come through the bulkhead from the Sw. A lag of voltage could indicate a Ign Sw going south. Wired to a mechanical relay would increase the lag IMO. An analogue volt meter might give a better representation of available voltage. On a digital like a Fluke your eye cant catch it. Cant remember what I used it for but sometimes slower is better. ABS wheel speed sensor maybe? But they are A/C V. ??

 

[Geoff 2]

The 8202 instructions clearly that a 0.8 ohm BR must be used with stock or points ign.
By stock, they mean what came on the car, which could be Chr ECU box or HEI if GM.

 

[71charger_fan]

I'm using one of these coils and have the start and run wires straight from the bulkhead to the coil.

60K Coils

I really liked being able to take the ballast and ECU off of the firewall. I also run a one wire alternator and an American Autowire harness.

 

[ncrobb]

It must have been the lag through the relay. When I jumped from the choke wire to the coil positive it started right up. Thanks guys for your input.

 

[diesel_lv]

So does your application require a ballast resistor? Quite simply, if your distributor has breaker points the answer is yes; if not, the answer is no. See all 7 photos 2 Older points-style ignition system used a single resistor which reduced amperage to the coil resulting in extended life for the coil and points.Aug 31, 2011
MotorTrend: New Cars - Car News and Expert Reviews › how-to

Did you read the original post??? HEI style ignition. Pretty sure that's "Not" points.

 

[ncrobb]

No ballast resistor required and the primary resistance of the coil matches what the HEI is looking for.

 

[Geoff 2]

Mike Brini,
Both of your posts on this thread concerning ballast resistors are incorrect.

Example: the Pert 1 module replaces ign points; but if the original coil is used with it [ & that coil used a BR ], then the coil still requires the BR & the Pert module requires full 12v. Can give other examples but not going to waste any more time....

 

[Don Frelier]

I have a crate 408" magnum stroker from BluePrint. The car is a 1973 Road Runner. The engine came with an external coil HEI style ignition. Knowing I would not need the ballast resistor or the electronic ignition box I decided to make a new wiring harness and not cut up the factory one. Well, I did, and everything works like it should except getting 12v to the coil. I removed the electronic ignition box and ballast resistor wiring from the circuit that comes out of cavity 23 (Ignition Run) of the bulkhead and now it runs just to the alternator field, voltage regulator and the electric choke. As stated, I removed the ballast resistor, so I ran a wire from cavity 22 (Ignition Start) straight to the coil thinking it would have constant 12v on cranking and run. It does not. So, I built an overlay harness with a relay to power the coil so the HEI would have a good 12v source. I got power from the hot stud on the starter relay and used a wire branching off from the choke as a trigger for the relay. Initially I removed the wire from cavity 22 from the coil but realized I wasn't getting power during the crank/start key position. So I hooked the wire from 22 (Ignition Run) back up to the coil thinking problem solved. Nope, it will hit like its going to start and as soon as you release from the crank position the engine dies. It runs great when I jump from the hot post of the battery solenoid to the positive terminal of the coil. I have checked my relay 25 times. I have seen diagrams and read threads saying to tie the brown cavity 22 (Ignition Start) wire and the blue cavity 23 (Ignition Run) wire together and POOF the coil sees 12v and runs. This is pretty much what I have done. In my case there seems to be enough lag between the start and run position in the key switch to cut the ignition and kill the engine. Any thoughts on how to better wire this or where I can pull a 12v source to trigger the relay that is powered during start and run?

A standard electo-mechanical relay is not instantaneous there is time between powering the relay and the contacts closing.
You need to find the two appropriate factory wires for start and run and remove the relay setup.

 

[Geoff 2]

Mike,
I understand what you are saying. I also have an extra 10 years on you in auto & elec experience.
However your explanation/understanding in post #18 is simply incorrect on a number of fronts. And it is not about a different perspective, it is about electrical theory. Which doesn't change for any of us!
The power surge in the coil occurs when the points closes the cct. Not when the points open. When the points open, a large back EMF of 200-400v is created & the condenser stops/reduces that arcing from pitting the points. The cond is not needed in elec ign systems [ inductive ].

The Bal Res [ BR ]. The purpose of the BR is to allow more coil voltage during cranking when the available voltage is reduced. The BR is shorted out during cranking so that with the reduced cranking voltage, the coil gets enough voltage to create a spark. Critical in cold weather.
Once the engine is running, the BR is in series with the coil. Apart from the starting advantage, the other advantages of using the BR is lower pri inductance which allows for higher engine speeds & the coil runs cooler, less current loss from coil resistance.