Go Back   VetteMOD.com > VetteMOD Technical Discussion > Electrical & Ignition

Reply
 
Thread Tools
  #1  
Old 11-08-2019, 11:23 PM
BBShark's Avatar
BBShark BBShark is offline
United States | Garage Monkey
 
Join Date: Mar 2008
Location: Right here
Posts: 4,472
My Photos: (293)
Default Ignition Wiring

I am installing a 69 ignition/engine harness in my car. However, my car has a mini starter (without an "R" terminal on the solenoid). My car also has an early 90's style HEI with a separate coil (not in cap).

Been looking at 90's wiring diagrams and, it appears that there is no need for the wire that runs to the "R" terminal and then to the coil. The coil only requires switched power (in Run and Start) and the solenoid only needs the purple "S" wire (and Battery).

Is this right?
__________________
Reply With Quote
  #2  
Old 11-09-2019, 12:32 AM
vette427sbc's Avatar
vette427sbc vette427sbc is offline
United States | Addict
 
Join Date: Sep 2008
Location: Jersey Shore
Posts: 909
My Photos: (87)
Default

Correct... the r terminal was to jump 12v to a 6volt coil during cranking. Not needed in your case
__________________
Chris
AutoWorks Middletown NJ
@autoworksnj
Reply With Quote
  #3  
Old 11-09-2019, 09:41 PM
mrvette's Avatar
mrvette mrvette is offline
United States | Phantom of the Opera
 
Join Date: Mar 2008
Location: NE Florida
Posts: 15,289
My Photos: (3)
Default

Quote:
Originally Posted by vette427sbc View Post
Correct... the r terminal was to jump 12v to a 6volt coil during cranking. Not needed in your case
YUP!!
__________________
"Hell, there are no rules here ... we're trying to accomplish something." Thomas Edison
I have a little list, let ALL of them be MIST......
Reply With Quote
  #4  
Old 11-10-2019, 06:54 PM
69427's Avatar
69427 69427 is offline
United States | The Artist formerly known as Turbo84
 
Join Date: Mar 2008
Location: Clinging to my guns and religion in KCMO.
Posts: 2,756
My Photos: (2)
Default

Respectfully, the R terminal shunt wire to the coil isn't there to provide 12v to a 6v coil (You won't find 6v coils or 12v coils in any electrical engineering manual). That shunt wire is there to compensate for low battery voltage during cranking in winter conditions where the battery efficiency is low and the starter motor is drawing a lot of current trying to crank over an engine/oilpump filled with thick oil. The shunting of the ballast resistor allows the coil to charge up to the desired amperage/energy level despite the battery voltage being low during cranking.

HEIs and (computer controlled) EST distributors have dwell control circuitry in them to extend the dwell period during low battery voltage/cranking conditions to sufficiently charge the coil for startup.

IIRC, HEIs were spec'd/designed to work down to 6v.
Reply With Quote
  #5  
Old 11-12-2019, 12:05 AM
vette427sbc's Avatar
vette427sbc vette427sbc is offline
United States | Addict
 
Join Date: Sep 2008
Location: Jersey Shore
Posts: 909
My Photos: (87)
Default

Interesting! What would be the proper terminology for a coil designed to work with a ballast resistor, and one without?
Reply With Quote
  #6  
Old 11-13-2019, 02:21 AM
69427's Avatar
69427 69427 is offline
United States | The Artist formerly known as Turbo84
 
Join Date: Mar 2008
Location: Clinging to my guns and religion in KCMO.
Posts: 2,756
My Photos: (2)
Default

Quote:
Originally Posted by vette427sbc View Post
Interesting! What would be the proper terminology for a coil designed to work with a ballast resistor, and one without?
To be perfectly honest, I don't know. In the engineering world, we have all the necessary electrical specs for coils/inductors, and that tells us what the inductance is (the main ingredient for storing energy), and it will tell us other stuff like the dielectric strength (what maximum voltages the windings can tolerate), or peak current/wattage to keep from burning up the wires/windings (and a few other boring details).

But, in the automotive world, those specs aren't always available. You (and I) frequently have to just use some rules of thumb, experience, and common sense. No ignition coil is going to be ruined just by hooking it up to 12 volts, as this is nothing compared to the 150-300 volts that the primary windings experience/endure every time the points open and the plug fires. The main issue to always keep in mind is the current level/magnitude in the primary windings. If you have a points setup, a decent rule of thumb is to keep the peak current in the 4 amp range. This prevents the coil from turning into a toaster oven if you leave the ignition on when the points happen to be closed. If you have an electronic switching system/module (that doesn't require a ballast resistor), you can generally run the amperage up a touch (5-6 amps), as most decent ignition modules will minimize the necessary dwell time to charge the coil, keeping the coil power-dissipation/wattage from getting excessively high.

Cliff notes: If you're running a 6v points system in a vehicle, most coils will work fine without a ballast resistor. If you use these same coils in a 12v points system, it's best to run a ballast resistor to keep the primary current (and wattage) from going too high. Electronic ignition systems (that don't use ballast resistors) can run higher amperage in the coils because the duty cycle (and internal wattage) is generally lower.

(Well, this certainly ended up being a longer answer than I intended.)
Reply With Quote
Reply


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 03:46 PM.
 


Design by: vBulletin Skins Zone
Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2019, Jelsoft Enterprises Ltd.