Question about HEI conversion and ignition timing.

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Dodgeboy68

Dodgeboy68

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I am working on doing an HEI conversion on my car that already has the Mopar electronic ignition. I am thinking that after completing the conversion that the ignition timing may change and require an adjustment. Has anybody experienced this.
I plan on doing a before and after check to see if the timing changes.

Thanks,
Roger
 
HEI Mopar Conversion Ignition with the 60,000 volt E-Core coil burns faster than a Mopar Electronic OEM set.

Hence instead of the factory recommended timing of 12° BTDC, you set the timing to 8° BTDC with the HEI/E-Core coil with your spark plugs opened up to .050 ths to make use of the hotter spark and keep the fireball in the best position to create power and efficiency.

Screenshot_20251117-181944_Gallery.jpg


NGK GR4 gapped at .050 ths running Non-Ethanol fuel.

Now since the Non-Ethanol fuel is over $5.00 a gallon, running the 85 octane blend at $4.00 a gallon I am sure has darkened up those plugs a bit.

Changing Times...
 
Don’t listen to a thing George is saying.

George Jets said:
HEI Mopar Conversion Ignition with the 60,000 volt E-Core coil burns faster than a Mopar Electronic OEM set
Click to expand...
Can you please tell me the physics behind the comment “burns faster”. What exactly burns faster? And how does the spark from an hei vs a mopar electronic box influence the speed at which whatever you’re speaking about “burns faster”.
 
Dodgeboy68 said:
I am working on doing an HEI conversion on my car that already has the Mopar electronic ignition. I am thinking that after completing the conversion that the ignition timing may change and require an adjustment. Has anybody experienced this.
I plan on doing a before and after check to see if the timing changes.

Thanks,
Roger
Click to expand...
What the engine wants for timing has many many variables that will influence it. How the spark gets to the plug is not one of those things.
Step 1 install HEI
Step 2 set timing to what the engine wants.
Step 3 drive and be happy.
 
Arbitrarily throwing any number (8 degrees) around for what the perfect timing is when the engine combination hasn’t even been discussed yet is asinine. I’m just sitting here shaking my head. @George Jets stop it please, just stop it.
 
George Jets said:
keep the fireball in the best position to create power and efficiency.
Click to expand...
Huh? Keep the fireball in the best position? How are you changing the position of the “fireball”? And this must be some magic fireball because now there is one single point in space where both POWER AND EFFICIENCY happen at the same time! I can’t wait to hear how you’ve tested this and recorded the results.
 
TT5.9mag said:
Huh? Keep the fireball in the best position? How are you changing the position of the “fireball”? And this must be some magic fireball because now there is one single point in space where both POWER AND EFFICIENCY happen at the same time! I can’t wait to hear how you’ve tested this and recorded the results.
Click to expand...
Too much Fireball? Can you have too much????
1785352484669.png
 
Just went out and pulled the #1 plug on the '89 Roller 318 4 bbl, Mopar HEI ignition running the 60,000 volt E-Core coil.

3 months putting around town on the 85 Octane gasoline. Pretty much the same plug coloring except for a little faint tan color on the spark plug electrode.

Not even worth a picture comparison.

Hats off to the HEI ignition for keeping the plugs burning clean, even with a lesser watered down fuel.

20260607_123803.jpg


.
 
George,
I believe you mean well but a lot of your info is plain wrong. You are correct about using HEI....a perfect ign system in this case. Going from Chrys elec to HEI isn't going to change the initial timing, if at all, that could be measured.

You keep sprouting the 60,000v E core coil. E core coil yes, 60,000v, no. I am going to spell it out...
In simple terms, Power [ heat ] in the spark = volts times amps. It is the HEAT that ignites the fuel; the voltage is merely the enabler to produce the current. The power is generated in the primary winding, & then transferred to the sec winding via magnetic coupling. If the voltage increases [ 60kv], then the current decreases. Tests that I have seen showed 28kv was enough to fire a 0.060" plug gap.
A 40 kv coil is more than enough, & all else equal, will produce a hotter spark & greater chance of the mixture igniting from the extra heat. And a 0.060" plug gap, not 050. Some cars came with 0.080" plug gaps.

img449.jpg
 
1) initial timing will be the same if you do not move the distributor
2) all timing after that will be miles out if you connect the pickup the wrong way. if it runs like crap swap the input wires around.
3) timing in general with it connected the right way will vary slightly due to the different electronics
4) it won't be enough of a change for most of us to notice
5) if you had any flat spots caused by lean or rich mixture they may be reduced as a better spark can ignite a poorer mixture than a weak spark. so in general there will be a seat of the pants feeling of the car running slightly better than it did, at all RPM. like there was when you replaced the points....

with it correctly set up, with a proper HEI coil and a stable 12-14 volt supply you are providing spark energy to each plug that is close to that of a MSD6AL gap plugs at 40 or so, your dizzy cap is small compared to real HEI Distributor, you don't want it to cross fire the wrong plug due to less than ideal phasing.

The 2 coils in this equation make or break an HEI set up
ignition coil needs to be an HEI one, get one from a 1976 Chevy 6 cylinder truck rockauto does them for $25 you will have to make a mount and buy a pigtail to connect

the pickup coil in the distributor should be a good match but if you find you have reduced RPM range is probably a weak pickup... the size of its signal is used to dictate the dwell control settings. a poor pickup coil produces a small signal. and the module thinks you are spinning 1000 rpm when actually you are trying to do 4000 rpm

the usual internet trope of HEI falls apart at 4000 rpm is potentially driven by this issue
the modules are good for way more if fed the right size of signal*.

* small peak to peak signal dwell control on hard you are traveling at low rpm or idling, spark time is limited to the max to keep the coil cool, plenty of time for max spark power at low rpm but you do not want the coil on for so long....dwell control on to the max so the coil doesn't burn up.
* big peak to peak signal, dwell control totally off, maximum power available at that rpm unleashed for higher rpm use
if you never get a big peak to peak signal you never get full power and dwell control stays on

Dave
 
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The initial timing will be off if you wire the pickup to the HEI backwards. Ask me how I know. :realcrazy:

It is possible the timing might move slightly if your HEI has wildly different latency numbers (the delay between getting a pulse from the distributor and actually sparking). So I would at least check with a timing light.
 
MadScientistMat said:
The initial timing will be off if you wire the pickup to the HEI backwards. Ask me how I know. :realcrazy:

It is possible the timing might move slightly if your HEI has wildly different latency numbers (the delay between getting a pulse from the distributor and actually sparking). So I would at least check with a timing light.
Click to expand...
yeah it will be out by a proportion of the wave form, i forgot about that, 1/2 to 3/4 of a sine wave signal from the pickup early by the look of things .

below a small signal = low rpm big signal = high rpm
triggers at a level above or below 0 volts and with it the wrong way round it does that on the down swing rather than just after the signal crosses the x axis on the up swing a place where there is little truly measurable variance between the 2 sizes of signal tiny variation. connect it backwards and get the "joy" of the bottom part of the graph, timing Out, rather than the proper execution shown on the top part.... i knew this so previously i was talking crap in point 1 :)

a backward trigger.JPG
 
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getting ready to switch from a msd rtr dist to a stock style dist and HEI. gonna use this coil. no way am i mounting an e-coil under the hood of our dart. would't look right. this one you'll never know is there.


1785408835803.png
 
I have seen one case where a different ignition required different timing. This was a nitrous drag car switching from an MSD 7 series to a set of IGN-1A coils, making several hundred hp per cylinder. And the coil near plug setup needed about 1-2 degrees more timing. What I think was going on is that the MSD releases its spark energy in a very short time while the IGN-1A gives a much longer spark with a lower peak current.

So with the IGN-1A system, the timing had to move because there was a longer delay between the start of the spark and the fuel lighting off. But that was a case of two wildly different ignition, massive cylinder pressure - and the difference was only a degree or two. If two inductive ignitions require a 4 degree difference in timing, something is very wrong.
 
That flame thrower will work all well and good
but not quite as effectively as the HEI coil
something to do with the flux density and core layout

it will be minimal i would think

everything is a compromise

although advertising your coil as very hot might not be wise
 
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Dave999 said:
you are providing spark energy to each plug that is close to that of a MSD6AL gap plugs at 40 or so,
Click to expand...
I’ve tested both in free air and the spark from an MSD box has much more energy and “snap” to it. For some reason I can’t find the video of the MSD test I did, might be on an old phone, but here is the HEI video. This is just a mopar electronic distributor with an e core coil mounted to my drill.

 
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