Hi, is fitting 123 electronic ignition straightforward on a series 3 and will the tachometer still work afterwards ?

 

I've got a Pertronix electronic ignition in mine.

I can't speak to how straightforward it was to fit initially; it had already been fitted when I bought the car.

But I had to replace the ignitor module once and that was straightforward.

The tach works fine.

Rick

 

There are two 123 distributor types; early one with pre-programed curves and later ones where you enter the curves yourself in EU metric units of measure. Lucas and US curves are in degrees of advance at selected RPM.
123 fixed curves are not ideal for long stoke street engines.. retarded at lower RPMs and Advanced at higher RPMs, but many Jaguar owners have found them acceptable. ( seems # 0 or # 2 work best most frequently).. Developing your own curve by finding correct Lucas Curve and converting it to absolute metric would be the best, but it requires some work.

From memory there were two types of Tach; one has the wire going to + plus side of ignition coil with power, the later Tachs, the wiring goes to the negative side of the Ignition coil. If you tach goes to the negative tab of Ignition coil, then there is no problem. (I have no knowledge if any one has had success with 123 with and + plus ignition wire system)

I went with the Pertronix also, as it has the correct ignition curve for the engine and modern available Octane fuels. It is plug and play for Tach wiring going to negative Ignition coil. ( Again no experience with + plus wiring from Tach to Ignition coil)
Rgds
David

Several threads on Programmable 123 distributor, if you go that way... A you-tube article from Europe on the programming helped a lot.
https://www.jaguarforums.com/forum/x...utions-278865/

https://www.jaguarforums.com/forum/x...epairs-210475/

 

My comments are for 6 cylinder XK engine, if yours is V12 engine, then others will have to comment.
Rgds
David

 

I think this will answer most of your questions

123 Installation on V12

 

Wow, not for the faint of heart!