View Full Version : Lucas Sport Coil Installation

11-03-2004, 12:53 AM
I have recently purchased a Lucas Sport Coil to replace my stock coil and am wondering how to correctly wire this into my '75 TR6. (The Stock Coil is Ballasted I believe.)

Currently I have a White, a Red and a Black lead connected to the positive terminal of the stock coil and then a White/Black lead connected to the negative terminal.

Can anybody tell me what the correct wiring configuration is to install the Lucas Sport Coil?

11-03-2004, 08:51 AM
jmayled, I would go with the same set up, just can't figure the Red/Black. Do you have an electronic ignition? Wayne

Geo Hahn
11-03-2004, 08:13 PM
I think the original coil on a 76 TR6 would require an external ballast (ballast wire) and the Lucas Sport coil does not. Therefore I would expect some change in wiring is needed unless the original coil has been previously replaced with a coil that did not need a ballast (sometimes called internally ballasted though I do not think there is any internal ballast, it's just a 12V coil).

I too do not recognize the red & black wires.

11-03-2004, 08:35 PM
On the '75 is the ballast wire and I wish I could remember an article I read somewhere about just changing a wire at the fuse box to get rid of it. I'll be back to you on that. Wayne

11-03-2004, 09:12 PM
Jmayled,My first questions before advising on the coil instalation are ; What polarity ground system is presently in the car? What symbols are on the coil's terminals that is presently in your car and which coil terminal connects to the distributor---Keoke

11-03-2004, 09:56 PM
jmayled, I have been looking at the wiring diagram for the '75-'76 which carried the ballast wire and the 72-74 doesn't. The one with the ballast shows a pink/white going into a white/yellow and as neither of these two show, you may have a car that got the old wiring harness before the changeover, in any case you can run a wire from the fuse box (white if you can) where the other white wire is and to the positiv side of the coil. If you can trase down the other white on the coil you may fine you already have what you want. Wayne

11-03-2004, 10:43 PM
Hi Geo Hahn, All modern coils that do not require an external ballast resistor are internally ballasted.-FWIW---Keoke

11-04-2004, 12:45 AM
Thank you all for your feedback. After close examination, the following color wires are connected to the positive terminal of the stock coil. A pink cable and White/Yellow cable and a black wire that connects to a blue resistor??
I've also read an article that suggests running an additional white wire from the fuse box to the Pos Terminal of the Sports Coil. If I perform this, should I remove any of the existing wires or simply reinstall them in their same location?

(Keoke: Negative Ground, Negative terminal connects to Distributor.)

11-04-2004, 01:10 AM
OK,Jmayled, Then Wayne got it straight out. Just replace all the wires on to the sports coil in the same manner as they are connected to the present coil.If you decide to go to a Pertronics Unit in the future You are all set.-FWIW---Keoke

11-04-2004, 09:48 AM
Jmayled, when you get everything going a couple of things to that will help your preformance and piece of mind are: open your plugs to a wider gap, and keep an eye on the points for oxidation, (the high spark can cause this). My plug gap worked best at .032 on high test gas, but another TR4 was better at .035, so it's kind of a shot in the dark for each car. Wayne

11-04-2004, 05:15 PM
Hello jmayled,
I suggest disconnecting the pink\white and the white\yellow and tape them up. The sports coil just needs a 12volt supply from the ignition switch (+ve terminal). For your information the pink\white is a resistance wire so will not give the voltage the sports coil needs and the white\yellow gives a 12 volt feed from the starter solenoid and is only live while the starter motor is running.


11-05-2004, 08:15 PM
Here's an article from the VTR Site (https://www.vtr.org/maintain/ballast.html) explaining the whole procedure of installing a Lucas Sport Coil. /ubbthreads/images/graemlins/cheers.gif

Geo Hahn
11-05-2004, 10:51 PM
A useful link.. I was concerned that we had jmayled somewhat confused.

Dan does correctly identify the Lucas coil as 'non-ballast' instead of 'internal ballast'. There would be no reason to put a ballast resistor inside the coil and then never use it -- they are simply built to deliver a correct spark at the full 12V.

As for jmayled's black wire with a 'blue resistor'... isn't that likely to be a noise suppressor to reduce ignition interference with AM radio?

11-05-2004, 11:10 PM
By Geo you're right again, I remember those things, but we mostly used them with the old tube radios to knock down noise. I also remember they didn't really do a lot to help until the carbon wires came out. Wayne

11-16-2004, 01:38 AM
Thanks guys - The Sports Coil was installed this past weekend following the guidelines layed out by trrdster2000.
The Spark Plug gap was increased to .032 (from .023 on the stock coil!!) which in turn provided a noticeable increase in performance.

11-16-2004, 10:01 AM

I have a Lucas sport coil in my TR4. I believe my plugs are gapped at 0.025. Does increasing the gap increase or decrease the tendency for the plugs to foul? Or does it have any affect at all?

Geo Hahn
11-16-2004, 04:24 PM
I use a wider gap and have not observed any greater tendency to foul, though admittedly I probably clean my plugs more often than I really need to.

I think the idea behind widening the gap is that you are not really taking advantage of the increased voltage unless you give it a larger gap.