S2 points ign - service or upgrade?

Hi All,

Have done some reading but still need some input from the team.

I have a stock 1978 S2L with fuel injection and points ignition. The FI system is now well sorted and I want to focus on ignition. This is a daily/hobby car and not a show/shine car.

The car currently runs well although the idle is a little rough and it stumbles occasionally when hot. The cap, rotor, and points look good (shiny!) and recent. The coil and related bits look as if they are original. Other than a visual inspection and timing light (idle) I have not touched the system.

I am struggling with the choice of maintaining the original system or upgrading to a S3 ignition system.


  1. Would you keep the points-based system with a complete service or upgrade? Why?

  2. I have no experience with points (other than dirt bikes last century) and the system appears fragile (resistor pack? 6V coil?). Is it more robust than I imagine?

  3. If I were to keep the points system, are there any practical upgrades to the system that will improve performance or reliability on a stock engine?

I see variations of this question have been asked many times but I did not find anything that I felt addressed this specific concept.

Looking forward to your thoughts,

Hi Jordan. Can’t say I have advice, but at least I can offer a few questions and comments.

What is your vacuum advance like? I’m not too familiar with S2, particularly the FI versions, but some cars had vacuum retard and some no vacuum system at all. If you have vacuum advance it’s a plus in favour of keeping your dizzy. And vice versa.

The S3 system with the AB14 amplifier seems to work OK–I’ve fitted one to my S1 car which has SU carbs, not Stranglebergs. But it’s ancient GM technology (the amplifier in the AB14 is a GM module that was originally in the dizzy itself). So unless you are considering “originality” even if retrofitted, my thoughts would lean towards getting a truly modern aftermarket dizzy and ignition system. Some of them allow you to select advance curves whilst driving, All IMHO of course.

Hi Jordan,

Part of “family fleet” (XJ6 SI, e-type SI and XK120) is equipped with the 123 ignition system, just becaise the original dizzies were in need of refurbishment. The modification is reversible and coupled to new cables and coil performs indeed well. You may consider that as well, as an upgrade to an SIII system.

I must admit though, that other than at idle and at higher rpm (>4500), the difference with a well-kept points system is not that noticeable.

As Robert says, the latest 123 (in my xk) is connected to the phone by bluetooth: the car can be immobilised with an app, and you get a useful display where you can trim your advance with great precision.

The biggest single advantage of 123-and the like is that the advance control is very stable and simple to adjust, but points to their job too.

Check carefully that you can still operate your amplifier, I am not sure about how it will work with your particular injection system.



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  1. it’s simple, on-road repairs are straight forward, but requires regular service. cleaning points and gap resetting for correct ignition timing…

  2. It is not fragile, it just needs regular attention…

  3. There are no upgrades to a points system. They worked perfectly well for countless years…:slight_smile:

Actually; the first electronic systems introduced still used the points - they just added an external transistor pack to carry the coil current. The weakness of points is that they carry coil current - which cause points erosion due to arcing as the points open - requiring regular cleaning, changing or gap adjustment for perfect function…

The main advantage of EI systems is that they require no regular maintenance - and basically generate higher spark voltage. Not really necessary - but they do for electronic reasons. The ‘weakness’ of EI is that if it fails on road; remedy is not immediately obvious, spares required…:slight_smile:

xj6 85 Sov Europe (UK/NZ)

Dear Jordan and Frank,

As Frank said, upgrading a points system no, but “performance-improving maintenance” yes: changing the condenser, setting gaps, and cleaning contacts. These are no upgrade to the system as such, but will probably upgrade the performance. Needless to say, cables, plugs and cap as well. In high mileage cars, think also of lobe wear.

I do NOT know the precise set up for your S2, but I would also check what coil options do you have, that increase the current: ethanol enjoys a strong spark. Possibly you will not use 85% ethanol, but in many places 15% is the rule (and yes, you feel it in idle quality, less so at high rpm).

Roadside repairs with a points system are indeed possible, provided you just keep a condenser and points (which I did, but they never failed…)

I never experienced in may years a failure on an EI system either (other than because of the CPS in an XJ40, unrelated to the dizzy).

In many ways Jordan, changing to EI, is like keeping carbs or going EFI on an older engine, just that the dizzy is more simple to swap and reversible.

To me the convincing factor to go for EI was to able simply adjust plots to engine mods, altitude and fuel (ethanol). I also max some of my cars (>4500 rpm, so I really want a stable plot, free of mechanical disturbance).

In case you go EI, my earnest recommendation is a Bluetooth system for ease of adjustment. In the XK, I stored three plots peaking at 24, 28 and 32 ° advance.

In case you keep Points, in addition to proper maintenance, also a mechanical / electrical overhaul of all ignition components.




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Thanks, everyone!

Excellent input and advice as always.

As the original system does not have any glaring inadequacies (other than maintenance requirements) I will conduct a full service and report back.

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Parts arrived last week. Rained out on Saturday. Car time Sunday!

Completed the following service work.

Changed plugs.

  • Plugs were all tan/white (lean?) and identical (no bad cylinders).

Changed wires.

  • Originals were resistance leads and old.

Did not change cap.

  • The cap that arrived did not have a cutout on the back and would not fit. Existing cap showed no carbon or pitting so it went back on.

Did not change rotor.

  • I did not want to change the rotor until I had the cap. I cleaned the rotor with Scotch Bright and reinstalled it.

Adjusted points.

  • Points were very tight.

Changed coil

  • Existing coil was damaged??? Maybe it swole? (is this possible?). In any case, the body of the coil was damaged and looked as if it had been clamped too hard. I swapped the terminals, cleaned everything, snugged the press-on fittings, and re-assembled them with dielectric grease.

Repaired resistor block

  • One white wire was barely hanging on by a few strands and the ground tab broke off. I crimped on a new fitting for the white wire and soldered the terminal back on. All are assembled with dielectric grease.

Wow! What a difference. It feels like a new car. I should have done this ages ago.

I am not sure if it was one specific issue or the combination of small issues that were causing my issues but the difference is hard to believe. The car runs so much better that it even shifts (kick-down) better??? My idle picked up at least 200 rpm and I had to reset.

Thanks again for all of your input.



Sure feels good to have the plan work!


and also thanks for the closing chapter. satisfies us. and completes the archives.


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Hi there again,

Good to hear: yes coils go bad in a few ways and overheat and swelling is a clear sign it’s dead.

I guess everything helps, but coil and resistors a big plus.

The cap can look new, but be carbon coated and conductive. One way of checking is measuring resistance between terminals with all cables disconnected.



That’s usual ‘problem’ with wholesale changes, Jordan - instead of changing one item at a time…:slight_smile:

You probably used more money than strictly necessary - but it was money well ‘wasted’! As material gradually builds up on the points the gap tightens - which alters ign timing. For that reason; normal maintenance includes filing the points with a points file before gap setting.

Your plug colour is as it should be. And normal maintenance is to clean and regap the plugs - with plug changes done only ‘as required’.

You have done a fine job - and are suitably rewarded!

xj6 85 Sov Europe (UK/NZ)


That brings back memories of messing with points. The rubbing block that runs on the cam wears. theat coses the point gap. Way back when, i was taught to lube them. “just a dab will do ya”. Most any light grease. I used petroleum jelly aka Vaseline, a lot…

Works great.


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Indeed, Carl!

xj6 85 ov Europe (UK/NZ)