One more Pertronix question

[bunzil]

Sorry guys,I'm not usually this brain dead. So I want to install the breakerless Pertronix in my '76 TR-6 which is ballasted and thus, from what I understand, requires a dedicated 12V source for the Pertronix versus hooking it up directly to the + lead of the coil. Am I correct so far? If so, what 12V sources has anyone used that makes a neat job of this...my car is stock, and I don't want to start running wires here and there. Or, for the sake of neatness, should I consider disconnecting the existing ballast (just where is it anyway?) and hooking the Pertronix directly to the + side of the coil?

Thanks.

 

[Brosky]

Pertronix hooks up with black (negative) to minus (-) and red (positive) to plus (+) on coil. Nothing else needed.

This is not the greatest picture to show you, but that's how mine has been setup for over a year.

 

[dklawson]

Pertronix does recommend that on cars with ballasted ignition you use a switched 12V power source. This precludes use of coil (+). They only recommend connection directly to coil (+) on cars using standard ignition coils.

I'm not versed on the TR6 fuse box so others will have to point out a good location to tap into. However, a general rule of thumb would be to trace back any of the heavy "green" wires in the harness of any Lucas system as these are generally switched 12V lines.

 

[Brosky]

I must have missed that in the installation instructions. My bad!

 

[bunzil]

Hi Paul,

Your'74, like my '76, should be ballasted assuming you kept it stock, although I note the Flamethrower coil installed. I'll perform the necessary measurements as mentioned by Pertronix in their site, but I am curious to know if anyone (you) has had success running the unit on a ballasted system. I really don't want to avoid any wiring. It's not a problem to install, I just want as stock as possible.

Ned

 

[dklawson]

When the Pertronix Ignitor is sold in the U.K. by Aldon they state the module can run from 6-16V which implies it will work directly by connection to the coil (+) terminal on ballasted ignition systems. However, Pertonix's PDF instructions in the U.S. have a half-hearted disclaimer about problems arising from operating with "low voltage" but they don't define how low... is low. They move on to talk about how to make a connection to a 12V supply when you run a ballasted ignition system.

In short... you could try running connected to the coil (+) and source a switched 12V connection point later if you determine it's necessary. I do have Mini owner acquaintances who have said they found it necessary to find the switched 12V supply. I don't know of anyone with a ballasted ignition running Pertronix with a direct connection to coil (+).

 

[bunzil]

Thanks. Paul in his reply above said he didn't run a separate line and he supposedly has a 74 ballasted car. His photo seem to indicate same.

I was asking elsewhere why are there two stock wires on the later cars going to the + side of the coil (in Paul's photo above too), and a little thinking has me going down this road: since the later cars coil crank at 12v but once started run at 6V, is it safe to assume one of the two leads supplies 12V at cranking, and then once car is running the first lead goes domant and the second, continues on at 6V? This would explain a lot. Naturally I can't find a thing in the regular manual. This being black magic and all.

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I don't know of anyone with a ballasted ignition running Pertronix with a direct connection to coil (+). [/QUOTE]

Except for the dummy in RI who didn't pick that up in the instructions and has been doing it for about 18 months, with no issues.

Call it dumb luck? Or maybe it doesn't matter as much as they say, or maybe I have just enough voltage to keep me out of trouble.

Yes I am still stock, with the ballast resistor in line. But that's easy enough to remedy, should you desire to do so and no one will ever know.

 

[bunzil]

For those following this thread, this link https://www.vtr.org/maintain/ballast.shtml
addresses the entire matter, and importantly, offers a very clean workaround using existing wiring. Nothing to splice, dice, or add. Very nice. So you can properly power a Sports Coil (or equal) in later TR6s, give the Pertronix the 12V required, and retain original wiring.

 

[bunzil]

Paul - try the solution offered in the link I provided above. It's dumb simple....which is good for me.

 

[Keoke]

Well yes it is simple. However, I would like to cloud the issue just a bit. 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. Confused--Keoke- /bcforum/images/%%GRAEMLIN_URL%%/grin.gif

 

[Brosky]

That's what I meant earlier about a simple remedy being available.

 

[tomshobby]

Thanks. Paul in his reply above said he didn't run a separate line and he supposedly has a 74 ballasted car. His photo seem to indicate same.

I was asking elsewhere why are there two stock wires on the later cars going to the + side of the coil (in Paul's photo above too), and a little thinking has me going down this road: since the later cars coil crank at 12v but once started run at 6V, is it safe to assume one of the two leads supplies 12V at cranking, and then once car is running the first lead goes domant and the second, continues on at 6V? This would explain a lot. Naturally I can't find a thing in the regular manual. This being black magic and all.

Hi bunzil,
The 12v side comes from the second small post on the starter solenoid, the first being connected to the ignition switch. When the solenoid is energized and makes contact it completes the circuit to power the starter and the second post witch provides 12v to the coil. When the switch is released the starter stops and the switch is no longer powered and there is no feedback through the post from the coil which is then powered through the resistor. When the starter is turning and there is 12v to the coil it has no effect on the resistor because there is 12v to both ends of the resistor at that time.

 

[Brosky]

The two wires on my positive side are coming from the Pertronix - 1 and the harness - 2. Perhaps that is my added 12V source and I didn't even realize that it was needed.

BTW, it's the same wire that is part of the stock harness, so I just left it alone.

Goes back to my "Dumb Luck" theory.

 

[bunzil]

Thanks. That makes sense and perhaps it's a matter of terminology, but the article I referenced above by Dan Masters alludes to something else. He says the last leg of the the 12v lead, before heading off to the coil, is energized at the starter relay - right next to the fuse box. It retains 12V as long as the starter is held. If the 12V lead remained live, then as you say, both ends of the resistor lead would see 12v.

To make life easy, Dan says all one needs to do is unplug the 12v (white/yellow) lead at the relay, and then plug it right back in at switched 12v source - the closest being an inch away, adjacent to the white lead coming out of the fuse box.
Is this your understanding as well? If so, that is one sweet solution.

 

[tomshobby]

To keep the benefit of a hotter spark when starting and yet have the coil at less voltage when running keep the coil connected the way it was originally. Unless your coil has the internal resistor. To run the Pertronix at 12v find the source of the pink/white (color on the 76) ballast resistor wire and splice in there. If you want less then 12v but more than 6v splice in somewhere in the middle of the ballast wire.

You may want to check the voltage from your ballast wire. Resistors tend to break down as they age and the result is less voltage as time goes on.

 

[bunzil]

Rather than chop up the harness for the benefit of a standard stock late model coil, with Pertronix, I'd rather install a Sports coil in addition to the Pertronix, if the installation turns out cleaner. Hence the earlier discussion about simply activating the 12v "trigger" wire for full time duty at the fuse box.

So that my understanding is complete therefore, do you agree with my points above that it can be moved from the starter relay, and that will do the trick?

 

[tomshobby]

Ned, I missed your second to last post when I posted. If you install a coil for an unballasted car you could do as you say. That is providing the new connection is only hot when the switch is in the "run" position.

 

[bunzil]

Thanks. What I am trying to do is make these nice upgrades (Pertroinx & Sports coil) while not carving up anything - that's the easy (and ugly) way out.

To make the switch, Dan Masters says "the resistor bypass wire from the starter relay to the coil (white/yellow) can simply be lifted from the relay terminal and moved to the fuse box terminal where the white wire is attached." That sounds simple enough.

But before actually doing so, a little testing seems in order. A 12 volt light attached to the white/yellow lead while it remains attached to the relay shows that yes, 12 volts is only seen when the starter motor is activated by the key. I would think, once disconnected, that the same lead would show no voltage once disconnected from the relay - but even disconnected it still shows voltage when the starter is activated. I'm suspicious therefore that this is the magic hidden backdoor to the coil.

 

[bunzil]

Tom, I think I have to go with you on this. The white/yellow wire swap recommended by Dan Masters will not work, at least on my '76. Hooking that lead up to any 12v source winds it's way back the starter and begins to spool the starter. Not good.

I've tested every lead, and there doesn't seem to be a magic path back to the coil to tap into that would permit a switched 12v lead. And the wiring diagram for the car is useless.

Perhaps tonight someone will have a brainstorm.