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Which ignition coil can handle constant 12V: UPDATE - car running

Canadian1968

Canadian1968

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I am playing around with the idea of the HEI ignition module swap inside one of our original orange boxes. Done a lot of reading it seems pretty straight forward. The biggest thing i have read, in order to take full advantage of this swap you need a coil that can handle a constant 12v. Unlike most coils that require the ballast resistor on our fire wall to drop working voltage to 8-9v range.

I know most of the articles say to use an E-coil, but I am trying to keep it looking stock with a canister style coil. Wondering if anyone has found a coil that can handle the extra juice.??
 
Look for one that has internall resistance of 1.5 ohms, petronix make one.
 
I thought the ballast resister was to protect the points from burning, not so much the coil? But in any event, a coil from any electronic ignition company whose instructions call for taking the ballast resister out of the system - Pertronix or MSD would be a couple.
 
It turns out an accel (super stock) coil I have has 1.4 ohm. Perfect !
 
Well after a bunch of reading both from different sites including MSD site itself, The coil on the car right now is a MSD street fire . Directly from MSD instructions it's says " if using points ignition a Ballast resistor MAYBE required " I stress that maybe point .

Anyway I did the hide away HEI 4 prong swap and the car fired right up. I hate to admit but the car idea smoother and the throttle response seems a bit more crisp .

BUT one thing I noticed . I took some readings before I unhooked anything . The regular mopat orange box and coil gave me a reading of 9.5v at idlel and a 4.5amp draw.

With the HEI module I am getting full battery - 13.4v but only 2.2 amps I thought that was interesting .

I wonder if u put in a matching E-coil if it would change that .

The car also leaned out quite a bit on my wide band..... very interesting . Waiting for rain to stop will take it for a drive next
 
HALIFAXHOPS said:
Look for one that has internall resistance of 1.5 ohms, petronix make one.
Click to expand...
I have a Accel SS chrome coil. It's internal is rated 1.4ohms. Are you saying this could be used on a factory Chrysler ign. system without the ballast? Will this be safe for my orange ecu also? I'm in the middle of this myself right now. Considering the HEI conversion also. Very confusing as far as ballasts needed or not with these coils anymore...(didn't mean to hi jack!)
 
You need a .5 ballast, depends what box you are running,

ecu chart 2.png


ecu III.png
 
Last edited:
If you use 1.5 ballast AND a coil with 1.5 internal resistance . Your putting 3 ohm resistance to your coil output. Your voltage off your coil will be pretty low
 
Geoff 2 said:
I think post #8 meant 0.5, not 1.5 ohm.
Click to expand...
So with my 4210505 orange box and Super Stock 8140c coil and a .5 ballast I'm good. That's how I'm understanding it at least. Didn't mean to hi jack your post man....easy to get lost in the search and discussion!
 
Apologies to Halifax, post #8 & 11. Thought he said 1.5 ohms.
 
JG,
I could not find a specific 8140 instruction sheet, only as part of the Points Elim kit. Extremely confusing. What I read is that you do NOT need a BR with the 8140 coil.
However, the chart in post #8 complicates things, using the Chr ECUs. Notice note #3 warning not to use below 2000 rpm prolonged use [ in other words, street use ]. Notice also the 0.25 ohm BR used. The rpm restriction could be because of the high current with this combination causes excessive heat build up in the ECU, the coil or both.
Sorry I cannot be of more help, but I would use the Accel coil has decoration on the mantlepiece & find a stock coil to use.
Chrome or yellow not going to make it go faster...
 
Canadian1968 said:
If you use 1.5 ballast AND a coil with 1.5 internal resistance . Your putting 3 ohm resistance to your coil output. Your voltage off your coil will be pretty low
Click to expand...
Not true.....coil resistance and ballast resistance are two different quantities and are not additive. The resistor LIMITS the current flow to the coil; the coil's resistance, along with the inductive reactance (how fast the coil charges or develops the internal magnetic field) and capacitive reactance determines the overall length of time and the strength of the magnetic field generated. The secondary voltage developed by the coil is a function of the primary to secondary turns ratio plus the strength of the magnetic field in terms of gauss or a measurement of the flux (magnetism) created to produce the secondary voltage ......its not a simple one to one relationship...... Just talking out loud.......
BOB RENTON
 
So your trying to tell me if I use the same ballast and hook one coil that's has .5ohm resistance and then one that has 1.5 ohm internal resistance I'm going to get the same voltage off each coil ?
 
Or the other way around. If you put a lower resistance ballast and higher your going to get same result from the same coil?
 
No, it acts like a voltage divider network looking at it simple terms. Proportion. 1.5 ohm coil + 0.5 ohm BR, coil gets 9v, BR gets 3v.
 
Canadian1968 said:
So your trying to tell me if I use the same ballast and hook one coil that's has .5ohm resistance and then one that has 1.5 ohm internal resistance I'm going to get the same voltage off each coil ?
Click to expand...
Resistance of the circuit is important but MUST INCLUDE the inductive reactance reaction combined with the capacitive reactions to determine how much and how fast the coil charges and discharges.....
BOB RENTON
 
RJRENTON said:
Resistance of the circuit is important but MUST INCLUDE the inductive reactance reaction combined with the capacitive reactions to determine how much and how fast the coil charges and discharges.....
BOB RENTON
Click to expand...
So basically just another one of your long drawn out responses using technical descriptive terms to answer a question no one asked ?

My original comment was correct. Pick it apart if you want. Using 1.5ohm ballast and 1.5 coil is going to give more resistance than he wants and lower the voltage. PLAIN and SIMPLE.

I was writing to answer his question and help problem solve his situation . Not a response to try and show off my knowledge and be graded by an electronic engineer.
 
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