Smoking new Pertronix unit

(peder) #1

My 420G with Pertronix ignition broke down a month ago. Petrol is flowing when I open a big nut at the float chamber.
I installed a new small black box with red and white wire. No spark from a plug with HT wire resting on the cam cover, but electric smoke is emitted from under the distr cap with ignition on.
I took the cap off and saw the outside of the small black box ”smoking” away.
What is going on here??? Wires are correctly connected to the new 105 Lucas coil.

(Phil.Dobson) #2

Can we assume the car was running ok with a petronix module within a lucas distributor before the break down?

Stating the obvious if you have smoke coming from the Petronix module (small black box?) then its safe to say that is now dead/broken.
These units can be supplied for either negative earth or positive so that needs to be verified.

Lastly the coil has to have a primary side resistance of 3 ohms to be safe.

Petronix module connections are connected across the coil observing the correct polarity.

(peder) #3

Thanks Phil, but it is yes to everything, which confuses me

(Phil.Dobson) #4

Please check the coil resistance with a multimeter

(Pete55Tbird) #5

Could it have anything to do with electrical system polarity? IE positive ground or negative ground. I am not familiar with the 420G.
Another thing is the Pertronix comes in three different versions and the igniter 1 (one) version will burn up if the ignition key is left on for an extended period of time. WITH THE ENGINE NOT RUNNING


(peder) #6

Itś a new Lucas, yellow 105 coil with 3 Ohm primary resistance

(peder) #7

Itś a new yellow Lucas 105 coil with primary resistance of 3 Ohm

Skickat från min iPad

(Phil.Dobson) #8

Pete makes a good point regarding leaving the ignition on for a period without the engine running. supposedly fixed on later models

(peder) #9

This happened on my 150 about 10 yrs ago when I was working on the stereo, but not this time on the G

(Erica Moss) #10

Peder, Your 420G is negative ground right? You’re certain you ordered the right module for that and connected the two wires correctly? Black goes to the minus coil terminal. Did you order the Igniter 1 or the Igniter 2? The latter is very sensitive to the type of wires you use. They can’t be stranded copper. They need to be suppression core (which they conveniently sell). That said, it doesn’t make the smoke come out. It just misfires like crazy and stalls out.

But as stated, if you smell smoke, it isn’t going to run now. It could have been DOA or it could have been miswired.

(Paul Breen pay palled it) #11

The unit that I have in our XJ6 is an Accuspark - the module must have a grey coloured heat conducting paste between itself and the mounting or it will potentially overheat and fail. Perhaps there is a similar need for the Pertronix?

(peder) #12

Thank you but don’t think it should have a paste.

But there is a small slot in the base plate, and I don’t know where, exactly, the black box should be. How close to the black round ”cam”???

(Paul Breen pay palled it) #13

I expect you could find this on the net for your model. For mine the distance is about 25 thou. Paul

(Erica Moss) #14

There is an FAQ about this exact thing on their website. IIRC correctly they basically said it doesn’t much matter so long as it isn’t really far out or brushing obviously. But again, that’s not going to result in smoke. Did you replace the cam magnet also or at least use the exact same type of Igniter module as you had before with it? I’m not sure if they’re compatible between the two module types.

(peder) #15

I installed a new unit, but the engine stalls after 5-10 secs. Fresh petrol, new plugs, and a good, tested coil. Starts on first attempt. (Pertronix ignitor in stock dizzy. Have run on the previous Pertronix for 6 yrs.
Very strange…:scream:

(tony) #16

You may have more than one problem contributing to poor engine operation, including excessive blockage of fuel due to debris in tank, filter, or seats.

In addition, I think it helpful to have known good original dizzy with points fitted.

This can be exchanged quickly, even in a 420G, where access is frustratingly difficult

I deleted the “air plenum resevoir tank”…serves no useful purpose, and hampers maintenance access…a one-way valve goes there instead

(peder) #17

Could be > one problem. Agreed.
I see in the car´s little Blue book that I increased the CO/richness the ptevious time out driving (a week earlier). I noted that it was 2-3 before and 5,5 now. That was using a normally trustworthy equipment at my nearby garage following a brakefluid change.
Drove home, and a week later the car started rough and died when idling outside my garage.
When changing plugs yesterday, I noticed how very sooty the plugs were. Thought it was due to the difficult test drive with a new ignitor, when the engine was started over and over again, following every stall.
Could it be that the engine, which with the new ignitor starts on first every time, but stalls after 4-6 secs, is quenched with an overly rich mixture…?

(peder) #18

I meanr drowned and not quenched, above

(tony) #19

if one of the needle & seats are leaking

one thing you could try is immediately switch off upon stalling, then remove a fuel bowl lid, if the bowl is empty starvation could be the cause, try both tanks, check the filter etc.

I also clean the tanks fairly often by removing the drain screw, or even better, the whole wire basket filter

there is always water & silt in the bottom

your symptoms dont really sound electrical…but they still could be!

(peder) #20

I know what you are getting at, and will check the float chambers next time I’m with the car.
But the question remains; can the overly rich mixture, which made the plugs very sooty, cause the engine to stall after a few secs of running?
And back to your fuel topic; it takes longer than a few secs to empty the filled bowls, after they have bern filled with ignition on, snd prior to pushing the button.
I have many Jaguars and have worked and driven them since 1984, but never had this situation. Carbs are in perfect order with new jets back in August😱