Ignition module locations ( hot temp)

Fact is, going from the dual coil scheme on the Lucas CEI to the single coil shouldn’t make any noticeable difference at all. Jaguar went with two coils because single coils with the required 0.6 ohm primary impedance weren’t available at the time. Today they are ubiquitous.

There’s also the matter of cost. The single coil Jaguar offers to replace the dual coils cost $90 last I heard, and that was a decade ago. Last time I bought one of those generic “bottle” coils with the 1.2 ohm primary impedance – also a decade or two back – I think it cost me $12. Now, with the way things are going, I expect today you can buy a non-Jaguar 0.6 ohm coil for a reasonable price somewhere.

Reliability? We had at least one member who had so much trouble with the single coil failing that hey went back to the two-coil setup. I dunno how either would be more reliable than the other unless there’s a particular problem with the specific coils used.

Thanks Kirby, I was kinda going with The Book and the Roger Bywater recommendation. But I swear the two coil set up is the original in my car from the factory. ( the Jaguar dealership won’t give me car maintenance history). I think they are original from the factory so let’s see what happens? I’m not even sure what would wear a coil out or what the indicator s would be besides total heat failure. Probably good time for a change if they’re 33 years old anyway.
Reading The Book seems like Roger Bywater was recommending it as a better Jaguar way to go but really not explaining why?

I replaced mine with the single coil, about $80 if I remember 2 years ago. Nice thing about the Jaguar one, no adaptations needed and you know it is the right ohms, etc.

No change as far as I could tell. A bad coil will reveal itself at high RPM. The main reasons I wanted to change mine were - age, and removal of extra wires going around the engine.

You’re right Greg, at the end of the day that was my main motivation. I was maybe trying to read too
Much into it from The Book from Roger Bywaters comments and thought maybe there was more to this. Maybe just a good modern upgrade. I’m still looking for the awesome smooth V-12 that we all talk about and I’m still noticing a slight hiccup once in a while at low idle. Maybe I just have too much time on my hands but I’m just going through the hit list. At the end of the day isn’t this why we always wanted a V-12? Arguably the most intriguing engine in a mass production car on the planet, bar none.

Similar path here. Wound up out front though.

It stays at ambient temperature now. Occasionally slightly warm after extended idling. No issues with water/moisture even driving in recent typhoon-like rain.


Hi @Jagrr881 can i know where you bought the amplifier?
I found it in Rockauto, not sure if it is the correct one as there seems to be different prefix when i google ACDelco D1906



That’s the correct amp.

At the end of the day I just ordered mine from my local GM dealership . It said made in the USA so I figured it was a good one. I have no issues, but from past posts on the forum some are not all created equal. Just watch for aftermarket knockoffs.

Thank you guys.
Will place the order.

So I finally got round to doing some measurements of my ignition amp. Those laser guns can be inaccurate, so i put one of these stickers on it.

After driving for half an hour, pulled into garage, it was 158F. Let it idle five minutes hood up, still 158F. Five more minutes idle with hood Closed, still 158F. Turned off engine and let it sit 10 minutes with hood closed, still 158F. But after 30 minutes sitting with hood closed, it was 171F. After 45 minutes, back to 158F.

1 Like

I also took some photos inside with hood closed, looks like there is about 1/2" clearance between my blue heat sink and foam padding. (1" if there were no heat sink.)

May not make a difference, but i cut out the second layer of 1/2" foam making a deeper air channel across heat sink.