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Triumph TR6 - Pertonix with Flame-Thrower

I have read all the good stuff in the archive but failed to find the answer to my question.

I intent to purchase the Pertronix PE-LU166A together with the Flame-Thrower coil.

I am now presented with the choice out of two coils one of 3 ohms and one of 1.5 ohms.
Pertronix indicates either City-use (3 ohms) or Racing-use (1.5 ohms).

Which way should I go? Lower resistance gives higher current results in better sparks?
Do I wear out spark plugs quickly if I take the 1.5 version?
What did you guy's do and why.

Given the present currency rating I would like to mail-order in the US. Is this lot any good or do you recommend someone else.

Thanks in advance,
Erik Creyghton

Hey Eric,

Since nobody else has piped up, I will take a stab at this.

I think the answer to this depends on what year your car is. Later cars should get the racing coil (1.5 ohms) since the stock wiring has a resistor (ballast) wired in. I can't remember what year this started, but mine is a mostly stock 74 and I got the 1.5 ohm coil. You can probably tell just by looking at the wires, i.e. if you see two wires going into the coil from the wiring harness, then it is probably ballasted.

Ignatius Rigor

Did you notice any difference when you changed your coil...their ads claim wider spark gap,more power,better milage,smoother ect
Charlie B.

Erik, I have the pertronix with what I suppose is a stock coil...I bought it this way. I'd like to know if the flame-thrower coil is a noticeable improvement (either performance wise or with regard to cleaner plugs and longer plug life. Also, what alternatives to pertonix are there and what to steer clear of
Sorry I'm no help but I can help float the post a little.

c.a.e. emenhiser

My mileage is up a 2 mpg to 18 mpg around town, and the car does seem to have more torque, but this improvement could also be me finally getting all my other settings right. I have been playing with the spark gap and the dizzy advance.

Ignatius Rigor

Erik--I've been using the Pertronix and the Lucas 'Sport' (gold) coil for several years with no major issues. The most notable improvement was in the quicker starts and zero time spent fiddling with the points. If you do the conversion, be sure to also get a set of good ignition cables (I have beefy magnecor KV85s) or you won't realize the true 'potential' of the setup.

Open up your plug gaps too; a reasonable starting point is 0.035. I did experience problems with the stock distriubtor cap getting worn out prematurely running with wide (0.040) plug gaps. It seems the Magnecors are so efficient that the aluminum distributor tower contacts were getting fried and tracked by the enhanced potentials jumping from the rotor through the wide plug gaps. This caused ignition misfires. After talking with Magnecor, I filed the contacts and gapped down to 0.030 at their suggestion to deal with the misfiring issue. The cap still requires maintenance, but at much less intervals.

Rick O.
72 TR6
Rick Orthen


My car is a model '74 and comes with a ballast resistor embedded in the wiring loom. The resistor is shorted out during starting operations through the ignition key. I understand your reasoning with respect to the 1.5 ohm version.

I am however puzzled why Pertronix uses the criteria City use or Racing use. I would expect them to use a more technical approach to the issue.


I will have a look to ignition cables also and widen the gaps on the plugs as you indicated.

I intent to overhaul the Lucas 22D distributor before I will change over to the Pertronixs. I am looking for an old one on the Internet to have some practice in before I attempt to disassemble the one on my car.

Perhaps some can still suggest me also a solid US internet shop to purchase the Pertronix.

Erik Creyghton

Erik- Please use the sponsor at the top of this page. He helps support this BBS.
Don K.


You are totally right, I should not have missed that.

Erik Creyghton

Eric- Before I opened my mouth I should have noticed you are in nether nether land. It might behoove you to check the English sites,but definitely get a shipping quote from LBC. Sorry for the quick typing and slow thinking.

For everyone on this side of the pond,
LBC is promoting Petronix Ignitor @ $72.50. The cheapest price I've seen. I am also in the market to acquire one.
If there is no decision on which coil to purchase, you can always get Flame Thrower in later days. So you can change over in steps.
Paddy Kan

I came across a MGB site which mentioned that:
If youe coil is ballasted, then use 1.5 ohm coil. Otherwise, a 3 ohm coil. Also in the same site, test shown the 3 ohm Flame Thrower is not that much better than the stock 3 ohm Lucas. But the 1.5 ohm Flame Thrower is hard to beat. The author even recommanded to upgrade the system to a ballasted one.
I wonder my 74 is ballasted?? I have a green wire comes out from the + of the coil, connects to a half inch cylindical object that looks like ground to the engine block. And a white wire comes out from the - side then connects to the alternator.
Can I check the coil with the multi-meter? and/or the cylinder shape thing?
Paddy Kan

Paddy, This is from Pertronix.
Determining whether your car has a ballast resistor:
1. With the key off, connect a wire from the negative terminal of the ignition coil to the negative battery terminal or ground it to the frame.
2. Connect the black (neg) lead of a voltmeter to ground. Connect the red (pos) lead of the voltmeter to the positive coil terminal.
3. Turn the ignition key to the "on" position. Do not leave the ignition key on for extended periods without the engine running.
4. If the voltmeter reads battery voltage (approximately 12V),there is no ballast resistor in the circuit. If it is less than battery voltage, there is a ballast resistor in the circuit.
5. Turn the ignition switch off and remove the wire from the negative coil terminal. Remove the voltmeter.

My early '74 has the ballast, though I've no idea where it is! I do know that it is a resistor wire in the harness somewhere nearby.
I've run with the Pertronics setup (pickup and coil)for the past 3 years, and would not change back. SC
Steve Crosby

Thanks, Steve
Are you running the 1.5 ohm coil? Mine is early '74 too. Have something to do this weekend. Will check next week.
Paddy Kan

A search of "Ballast vs non ballast " will give some details on which coil to use. It all has to do with that ballast resistor in the wiring harness. If I recall the thread is way back around 1998-99.
Rick C
Rick Crawford

Paddy, I have to be honest and say I don't know the resistance. I just ordered the coil recommended for ballasted applications. Moss part No. 143-270.
Steve Crosby

I checked using your instructions. It is 5.7V. So my system is ballasted.
'74 TR6
Paddy Kan

This thread was discussed between 23/01/2005 and 05/02/2005

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