using GM Delco ignition system Parts

[mrclubike]

Here it is from the inside with out the rest of the guts

And here it is mounted up

I was able to run it today   
The HEI IGN module quickly got extremely hot with the GM DIS  coil
So  am going to have to go to a higher resistance coil

When I was bench testing everything with a 3 ohm coil I did not have this problem 

[Barry]

Does the HEI module have any internal dwell control to limit coil heating ?  Short of hooking it up to an oscilloscope, one way of checking would be to measure the primary current through the coil. Modules with dwell control often limit the current to something like 7 Amps. If there is no dwell control a coil of such low resistance will pull much more than that.  I don't think I would want much more than 7 amps as the ignition even ion average current becomes a significant load on the charging system.

[Barry]

Does the HEI module have any internal dwell control to limit coil heating ?  Short of hooking it up to an oscilloscope, one way of checking would be to measure the primary current through the coil. Modules with dwell control often limit the current to something like 7 Amps. If there is no dwell control a coil of such low resistance will pull much more than that.  I don't think I would want much more than 7 amps as the ignition even taking into account the average current becomes a significant load on the charging system.

[mrclubike]

From what I  have read I think they do but it may be inoperative when it is triggered with the hall effect or with points
They were triggered with a Inductive  type sensor in the GM application and not held on like it is in this application

I did install my 1.5 ohm Dyna coil and i left the key on with it not running and it barely heated up

I will try to run it tomorrow and see what happens 
I wish I did have a scope  to see what is going on

[mrclubike]

I went for a thirty mile ride today and checked the temp of the coil and IGN MOD periodicaly
Every time I checked them they were just slightly warm to the touch

So as it stands now
I have my spare Hall Effect mounted to my hand made bracket. That mounts to the can from the outside.
The GM Delco HEI Module and a Brown 1.5 ohm Dyna Coil

[mrclubike]

Does the HEI module have any internal dwell control to limit coil heating ?  Short of hooking it up to an oscilloscope, 

I hopefully I will know by the end of this weekend
I have a Oscope coming and I am going to try to figure out if it does

[mrclubike]

OK 
This is with a 3ohm Dyna coil

I tested the dwell with an Oscope and I found their is no difference  between the Bosch Ign Mod and the GM HEI Mod
 
You will notice that the dwell in both cases   match the signal from the bean can precisely

Measuring out to be 60% or 108 degs
From what I have found on the net is dead on 
I checked it   at 1000 rpm and  4000rpm with no change 

From what i can tell it is only dropping the voltage to the coil about 1 volt no matter what the rpm is 
 It may start dropping or compensating with a lower resistance coil but I have not checked it with a lower resistance coil yet
When i get time I will check it with a.7 ohm Dyna coil

I have a secondary voltage prob and amp prob coming
Then I will check the  secondary voltage and primary amperage with a 3 ohm and .7 ohm and see what happens

[Barry]

Good stuff. So the hall sensor provides a fixed dwell. It now seems unlikely that there will be speed related dwell control even with the 0.7 ohm coil but it will be interesting to see if it limits the maximum current. I think it must do.  I noticed the Vce voltage drop across the output transistor as a small reduction in current compared to a points set up with the same coil.   To say I'm rusty on electronics would be an understatement but I wonder if Vce will rise as the current increases with the 0.7 ohm coil.  That in itself will limit the current flow at the expense of a lot of heat dissipation. I would have thought current limiting should be more sophisticated than that though.

[georgesgiralt]

MrClubike,
I was told that the latest BMW OEM electronic modules have a modified circuitry able to provide dwell control and current limitation at the coil in order to accommodate the old crack-o-matic gray coils and the new improved coils.
Of course, this could well be urban myth but then why change P/N ?

[mrclubike]

Here is a picture of the Bosch mod I am using
I do not know if it is original to the bike
It does however shut off the power to the coil when the motor is not cranking
According to Snowbum may indicate it is later but it is difficult to know 

[mrclubike]

MrClubike,
I was told that the latest BMW OEM electronic modules have a modified circuitry able to provide dwell control and current limitation at the coil in order to accommodate the old crack-o-matic gray coils and the new improved coils.
Of course, this could well be urban myth but then why change P/N ?

 I have a feeling this is correct
I am thinking the Alpha electronic advance Mod have modified this circuitry to change the timing along with the dwell

[mrclubike]

Good stuff. So the hall sensor provides a fixed dwell. It now seems unlikely that there will be speed related dwell control even with the 0.7 ohm coil but it will be interesting to see if it limits the maximum current. I think it must do.  I noticed the Vce voltage drop across the output transistor as a small reduction in current compared to a points set up with the same coil.   To say I'm rusty on electronics would be an understatement but I wonder if Vce will rise as the current increases with the 0.7 ohm coil.  That in itself will limit the current flow at the expense of a lot of heat dissipation. I would have thought current limiting should be more sophisticated than that though.

I do not have the latest Bosch OEM mod to check
But I do have the Alpha Emerald Island sytem (electronic advance) that I will throw on and test

[mrclubike]

After over 3000 miles Still running the Delco Ign mod and a 3ohm Dyna Coil
with my quick change hall effect sensor and  have had no problems
It does start better but who knows if this is the reason for that   or not

The Delco Reg and Diode board is also working just fine but the rotor did fail about 2 weeks ago

[Justin B.]

I see a new "garage business" in your future!