One more Pertronix question

[tomshobby]

I know, but you had to be sure in your own mind and that is a good thing. You will get it worked out.

 

[TR3driver]

1St, all coils are designed to operate off of 6 Volts. Therefore, when 12 volts came into use an external ballast resistor was the simplest method to integrate these coils in the 12 Volt ignition system and they were called Ballasted coils. Later in production the ballast resistor was included inside the coil itself [Lucas Sport/ Flame Thrower etc] and these are referred to as Unballasted coils.

A more accurate way to look at it is whether the coil requires an external ballast or not. Early Triumphs used the so-called "12v coil" that did not require a ballast; the switch to coils that did require an external ballast was to provide easier starting on hard-starting emissions-controlled cars.

Many modern coils are marked "12v, ballast required".

Also worth noting that the "Lucas Sports" coil comes in both flavors, so don't assume ...

Randall

 

[Keoke]

What the coil is marked and in fact what it is, is two diffwerent things.--Keoke

 

[Brosky]

Ned,

So after all of this, are you going to wire it like mine and just get in and drive it? I have the Pertronix coil and Igniter for my "stock" 1974 TR6. Works just fine as shown.

 

[tomshobby]

And the winner is....Exactly, if the voltage is above the lower limit why not!

Trying to explain how it works sure took us in a circuitous route. Pun intended.

 

[bunzil]

I am thinking of trying your method Paul. I'm getting well over 9.5 volts out of the resistor wire, which just might work.

For me, it's not about maximum performance, but enhanced performance where available, with maximum reliability, and as little cosmetic changes as possible.

As always with these cars, it's a fun exercise. In this case, seeing that Dan Masters is seemingly wrong, for my application anyway, doesn't make him wrong. It just proves again that we all need to second guess and double check outselves. This is a great forum...no doubt about it.

 

[dklawson]

I read part of Dan Masters article at the link posted earlier. I don't remember the details about the yellow/white wire position swap so forgive me if I'm misunderstanding the posts and comments above.

If you want to move the yellow/white wire to power the coil with 12V you have to move it from its connection at the starter solenoid, leave it connected to coil (+). Seek out a position in the wiring harness or on the fuse box where there is a heavy gauge white wire. On LBCs w/o ballasted ignition systems, the white wires were used for switched 12V to power the coil and electric fuel pumps. If you move the solenoid end of the yellow/white wire to a white wire connection point you should therefore have the 12V you need. (Remembering of course that you've left the other end connected to coil (+) ).

 

[bunzil]

Thanks Doug. No problem on Dan Masters, but what he says with authority in that link won't work. At least the way he describes it.

Your explanation does however and too bad the wiring diagram for the 76 is incorrect. Can you confirm, for those of us in the back of the class, just one more time; is the yellow/white wire coming from the solenoid indeed dedicated solely for the purpose of giving ballasted systems like mine a full 12v to the coil at cranking, and nothing else? If that's the case, then what you suggest makes perfect sense and disconnecting it from the solenoid, and feeding it by a ignition switched white is the way to go.

 

[dklawson]

Cars built with ballasted ignition typically use a solenoid with four terminals (battery power in, start power out, input from the ignition switch, and the terminal for the ignition coil. ) This ignition coil terminal is switched on only while the starter is cranking.

Take a look at Dan Master's company web site for an example wiring diagram:
https://www.advanceautowire.com/tr2506.pdf
Scroll through that document to page 5, '73 TR6
In the top left corner you'll find the starter motor with solenoid attached. You'll see the yellow/white wire leaves the solenoid and goes directly to coil (+). No device other than the coil uses the yellow/white wire for power.

EDIT: I should have mentioned.... Page 5 of the PDF is for a "pre-engaged" starter where the solenoid is piggy-backed on the starter motor. Subsequent pages for later TR6 models show a separate starter relay (solenoid). You'll see the four solenoid terminals I mentioned if you look at those later cars. (Technically there's a fifth terminal... ground. )

 

[bunzil]

Doug. That's perfect and the mystery solved. Indeed, Dan's diagrams (now printed) explain the situation and yes, my car has the four terminals on the solenoid, one of which is yellow/white. Regardless of how I finally resolve this matter, there's comfort in having the full understanding you've provided.

Naturally after all this, it might just be easier to run a new white wire to the coil from the fuse box, versus disconnecting the yellow/white at the solenoid. I'll see.

Thanks a million.