It will be fine. If your wires are old they should probably be replaced. Look under the hood with the engine at night and look for sparks.

If your engine ran before, you did not change the timing, and you have spark now, it should run. As others have said, check your timing. Did you disconnect any plug wires? Check for crossed wires.

Fat blueish spark. any other color and something is off. I would have tried to rewire the HEI before installing the relay myself, then added it to the mix if you wanted the suggested relay.

Here is a VERY simplified 'drawing' of the HEI schematic.....

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MRO....

Cheap, Fast, Reliable.... Pick 2...

looking at the spark in the daylight under shade, my Dad says it looks kind of an orange color to him. We still have power to the coil and module and do have a spark, it just won't start up. Starter just runs but nothing hits and seems worse than yesterday, when then it at least sounded like it was trying to start up ( and did once).

How mush voltage do we need to have at the trigger wire on the relay? I'm using the blue wire that would go from the ballast to the + side of the old coil and we are getting power to it when the ignition is on but it shows 11.75-85 voltage, which is a bit less than full voltage from the Batt which is around 12.75-85. ?? Should I try to revert things back to the ECU box, put the ballast resistor back in and see what it does? Could I do that with the new E core coil? Or would I need to use the can coil?

Have you tried changing the position of the leads coming from the distributer to modual (right to left and left to right) ?

Richard

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Part of Tyrde-Browne Racing

Thats the sign of weak spark
It needs to be a full 12v for the components to work properly For the trigger wire the 11.75 up voltage will be fine. Yes thats low, you have a voltage drop somewhere. You need to find where the voltage drop is occurring.


You can in reality pull the energized side of the relay from the battery directly. (not sure where you are trying to draw from) I wouldnt, you just have a low voltage situation somewhere.....
But if you revert back to the factory ECU, it would be simpler to use the can coil. BUT not non doable....

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MRO....

Cheap, Fast, Reliable.... Pick 2...

yeah we did that and couldn't notice a difference

OK so I need 12v to the coil, to the module, and the wire supplying the trigger needs to be 12v too? or can the trigger feed can be less? (like 11.75v ) I'm drawing power for the HEI via the relay, directly from the Alt.

we went ahead and reverted back to the factory ECU, ballast resistor, and old can coil just to see what would happen. Still it won't start up, sigh! FORGIVE my ignorance but in this original set up, what voltage should we be getting at the "+" side post of the coil with the ignition on? I think since we're now going back through the B resistor we shouldn't be seeing full 12+ voltage, but something half that ...is this right? I'm getting about 6.50v.

If there's a problem w/ the old can coil, what's the best way to test it?

If you are referring to the "trigger" side of the RELAY yes the less than 12v is fine as long as its operating the relay.

The "bat" post of alt, right? (large post on rear of alt) {edit, i did see the post telling us}

There are only 2 places the 12v is ran to.

The + side of coil and the B TERMINAL of the module.

Just as i have in the drawing.

Module wiring:
B- BATTERY + 12V
C- COIL - (NEGATIVE SIDE)
G- TO DIST
W- TO DIST


Now as to why the factory style ecu wont start it, tells me that there is a problem with most likely the ignition switch it self. (not passing voltage while cranking) That is my first guess. Bad ignition switch.

You cant test it by running a wire from the battery directly to the relay trigger (on the hei) and try to start car with the key.

What year of car are we dealing with? (may have missed that in another thread) and is it a dual ballast resistor or single?

The voltage after the ballast sounds about right altho i am unsure. I can check my car tomorrow and see what the voltage is for a +/- value.( maybe a volt one way or the other...) but you are correct it will be less than the battery voltage. I think its a timing issue, or when replacing the bulk head connector you got a wire miss placed.


After re-reading the whole thread, make sure you have a GOOD battery. (ie: fully charged) All the cranking that has been done can drain it to less than optimal voltage for either system to operate. ( use jumpers if needed)

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MRO....

Cheap, Fast, Reliable.... Pick 2...

Right now the older ignition system (ECU) is in place, I reverted back to see if it would work. Since I;m still in that set-up, and since you suspect a bad ignition switch, how do I test for a bad ignition switch in the ECU set up? Or do I need to hook back the HEI to test it?

My car is a 1968 dodge dart 270 slant six 225, it has been my daily driver for over 3 yrs now and up until recent electrical issues ( which prompted this project ) has been extremely reliable. Last time I had it tuned and timed up was in Jan 2012, even had the the valves adjusted( although they were basically fine when checked). We did check the timing and it was fine as of last Thursday and it's still good as of yesterday ...didn't know trying to switch to the HEI would mess that up so badly, assuming it did, and it is. With my car being down I have no transportation and bumming rides is the pits!

I was just referring to the weak/no spark during cranking. Thats the reason for the statement about the ignition switch. If your sure that the wiring is correct (as its new) thats the only other place that hasnt been looked at.

(Using the factory ECU the start circuit wire{sometimes referred to ign#2} runs the full 12v to the coil only, the ECU uses the stepped down voltage)

So after I dug around and found the diagram I was looking for, a wire ran directly to the + side of coil from battery,then try to key-start the car.

As I said make sure the car is cranking 'normally'. (full charged battery)

HTH, or if not we will keep plugging along till we do get it right.

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MRO....

Cheap, Fast, Reliable.... Pick 2...

Unfortunately had to work painting all weekend so I did not get a chance at my car. So I hope to check some of the things you mentioned tomorrow.

What your saying, if I understand correctly, is that with the factory ECU in the mix, the + side of the coil should see 12v, the ECU should be getting half that (stepped down voltage) and not sure what we should get on the coils negative side. Like I said before, when I turn the key to the ON position, I was getting 6.something volts at the coils positive post. I did not check to see what the coils + side was showing when trying to start, perhaps that's when it should show 12v ....I'm probably sounding like a real dummy, so thanks for putting up w/ me and for all the help

Scott,

Your coil will only see a full 12 volts when you have the key all the way over cranking....on start up, then it drops down to about 6 volts after going through the resistor when the engine is running.

I tossed the resistor a few years ago and bought a Pertronix 3 ohm HEI coil so I can run the ECU and Coil with a full 12 volts plus....works great with a .045 plug gap. The ECU runs on a full 12 volts just fine. I have been running mine for a few years that way.....

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Aggressive Ted

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74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Okay, finally found time to test on the car. Here's the results..

Have checked and re-checked the wiring, looking for any bad connections or continuity loss, anything, and I can't find a problem.

1. Tested voltage for the ign 1 wire ( run side of ballast ) with the key ON, I get 11.60+v (always get about 1 volt down from the Batt voltage) I get 6+volts, when trying to start up. The specific wire tested is blue w/ white tracer and it starts at the ignition in car, runs through the B-head connector to the ballast.

2. On the ECU box I get 11.60+v, testing the light blue wire w/ tracer that splices in with the ign 1 "run" wire

3. Testing at the ballast resistor, on the brown ign 2 ( "start" side wire ) that also comes from the ignition switch in the car, I get about 6+ volts when the key is "ON" and only about 9+ volts when turning the key to start ( crank)

4. The blue wire along side of the brown, also on the "start" side of the b-resistor ( this is the wire that run to the coils + side ) I'm getting 6+ volts at the coil with key ON. When I turn the key to START, I get 9+ volts, again at the coil.

5. If I pull off the plug connector at the ECU box and then grab and test the wire at the coils + side, I get 11+ volts. And when I put the plug back on the ECU, it naturally knocks the coil volts back down to 6+.

6. My battery is good and we also have a charger just in case that helps add power when needed for these many tests. By the way, I tried running a wire directly from the + side of the battery to the coils + side and tried to star the car ...with know luck. I noticed that the battery itself drops in voltage when the starter is trying to crank. From 12.75 to 10.50volts, and so when we ran direct from the batt to the coil, we also got 10.50 volts when trying to start.

That's all right now ...I hope with this info someone can spot a solution and soon...

Probably just flooded now. Make sure you have the coil wire on, and check the timing. If it ran before, it should run now.