Ignition Wiring

[ebc699]

I recently managed to fry the module in the Petronix ignition (my own fault, but we won't go there) and want to change back (temporarily) to the points and condenser. We are moving house in the next few weeks and need to get the Plus 2 going!
When the Petronix was installed, I had the usual trouble with the bouncing tach but took it to the local instrument shop who got it working again. Now when I come to connect up the original points system I'm unsure just how to do it. Originally, the (white) wire went from the ignition switch, did a loop within the tacho and then to the positive side of the coil. However, since the mod to the tacho, there appears to be just a wire going to a terminal on it with no loop.Obviously the white/black wire from the side of the distributor would still be used, but other than that I'm stumped.
Ultimately, I'll be going back to Petronix which has been very reliable but really need to get motoring again.
Any help would be appreciated
Thanks,
Wylie.

[RichC]

Sounds like you're negative earth. Presume u don't have wiring diagram to hand. Would you have 2 wires coming from main loom in vicinity of coil. Black /white and green/red and another plain red?

[john.p.clegg]

Just for the move " hotwire " it,Live to the + of the coil , points to the - of the coil..( assuming neg earth )

John

[billwill]

Your tacho have been converted to voltage-triggered so the loop through detector is not needed now.

So the white wire that looped through the tacho simply bypasses that now.

I expect that you simply replace the pertronix with the original contacts, replace the capacitor/condensor that used to connect across the points and then connect the wire (that used to go to the pertronix) to the points.

[ebc699]

All now sorted. Thanks for the input.
Cheers,
Wylie.

[yacalo]

Hi -

I have a new Petronix Flamethrower distributor for my Lotus Twin cam engine - unfortunately I will have replaced my the Pertronix Module Ignitor II British two times now and it appears to have just failed again after jut 50+ miles..

I read on this post that the 'bouncing tach' issue is common .. are the two issue related?

What might be causing the problem?
Do you have any idea how to resolve the issue?

Any help/advice gratefully appreciated - novice +2 owner here.

[Donels]

I was reading the (Aldon) Petronix installation info the other day and noted that it cannot be used with a sports coil and should be a standard 3 ohm coil otherwise it can cause failures. Check what coil you have.

[yacalo]

Thanks Donels - I had added an external resistor - maybe that wasn't enough to protect the Module Ignitor .. Just bought a new coil and ignitor. Will share if that solves it.

[yacalo]

Thought I would update this topic - I have changed the Coil back to Petronix and replaced the Module Ignitor with the same part (Pertronix REPLACEMENT IGNITOR II MODULE FOR ALL FLAME-THROWER"STOCK-LOOK" 4 & 6-CYLINDER 45D STYLE DISTRIBUTORS, Black, (D500701).

So far it is working but I am already beginning to see some occasional misfiring..

If it fails again - having spoken to Mountune - they recommend another much pricer part which I may need to cough the $625 dollars for..
https://mountuneusa.com/products/lucas- ... ford-lotus

[2cams70]

I’d recommend chucking out anything that’s called “Flame Thrower” immediately and putting it back to standard points. It might start an engine fire.

[mbell]

So far it is working but I am already beginning to see some occasional misfiring..

Have you ensured the igniter module has good thermal connection to the dizzy base plate? I think most failures are due to heat either ignition left on and current flowing or bad thermal connection. (Along with QC issues if tehy fail very quickily).

When I fitted one to my car, I made sure it was fully level on the base plate and used some thermal paste between the module and base plate.

You also need to confirm your ohm coil you are running. If you run a 1.6 ohm with no ballast resistor the coil will overheat. You need 3 ohm coil or 1.5 ohm coil and 1.5 ohm ballast (make sure it is wired in series with the coil in the run position.)

they recommend another much pricer part which I may need to cough the $625 dollars for.

That is a lot of money. IMO a 123 dizzy would be much better buy for a road car that didn't require original dizzy or points.

I also think the advance curve on it is wrong for a twincam. 12 degrees of advance, gives only 24 if you set it at 12 degrees static. My experience has been the engine really benefits from more advance (32-34 degrees) and at lower rpms.

[yacalo]

Thanks Mbell - hadn't thought of the thermal connection..

No I haven't added any thermal protection .. that could very well be the problem.
I am running a 1.6 ohm coil with a ballast wired in series with the coil

Are you suggesting I apply something thermal protection like this Castrol Optimol TA Assembly Paste (see link below), between the module and the dizzy base plate, then screw it back on? Or should I apply it directly to the module itself to shield it from heat?

I think you may be spot on with your diagnosis as the module appears to fail after extensive driving, likely when it has endured sustained heat..

https://www.ecstuning.com/b-genuine-bmw ... S4QAvD_BwE

[ericbushby]

What you need is a heat conducting paste as used between thyristors and transistors and their heat sink.
Most people involved in electronics will have it. A thin smear is all that is required.
Sometimes, as on my hall effect module, their is a `pip` on the base plate which would prevent close contact. This needs to be ground off.
The heat which would damage the module is produced inside it so conduction is what you want not insulation.
Best of luck
Eric in Burnley.
1967 S3SE DHC

[mbell]

What you need is a heat conducting paste as used between thyristors and transistors and their heat sink.
Most people involved in electronics will have it. A thin smear is all that is required.
Sometimes, as on my hall effect module, their is a `pip` on the base plate which would prevent close contact. This needs to be ground off.
The heat which would damage the module is produced inside it so conduction is what you want not insulation.
Best of luck
Eric in Burnley.
1967 S3SE DHC

Yes this.

I used a high end thermal paste from computer CPUs. As I had it lying around. I can't remember if I had to modify the base plate to remove the pip, but I'd strongly suggest checking that.

I am running a 1.6 ohm coil with a ballast wired in series with the coil

Do you have the ballast bypass wiring for starting? Are you certain that the ballast inline when running?

If not you'll likely overheat the coil after longer running period. (I experience this when restoring the ballast to my car and got the two ignition connection backwards)

[Lotus 50]

I tried a Petronix and before that some other pointless ignition that I have mercifully forgotten. Both wound up with my car being towed to a repair shop and conventional points installed. It's my understanding that pointless conversions are generally good, but not my experience.

At 1000-1500 miles a year, I can get the points adjusted hardly ever and have no concerns.