Question on drive shaft of 123ignition distributor

As part of a rebuild, I replaced the original Lucas distributor with a 123 ignition unit. This was 2y ago. The car has been a slow rebuild project. I took it for its first run a couple of weeks ago. Ran fine, but then started to splutter after a few minutes. After various checks I found that the car ran fine with the old dizzy back in (I kept the new coil in place). To make sure that this wasn’t just pure chance, I swapped the dizzys a couple of times. It definitely runs very rough on the 123 unit. Unfortunately the original Lucas is a little worn but definitely runs ok. One thing I noticed - and here’s the question - is that the shaft is noticeably longer on the Lucas distributor than on the new 123Ignition unit. Could this cause issues? I know the off-centred dog locates in only one position in the engine - that’s fine. But is the lack of a centring shaft section going to cause me problems? Also wondered if others had had troubles with their 123’s. It was very straightforward to instal and setup.


When I installed mine, the clamping ring interfered with the distributor seating completely. Try removing the ring and checking to see if it seats completely. I had to pry open the ring before it solidly engaged, and but since then, no problems.

Some 123 distributors ship ship with crap caps. My 123+ came with a loose fitting cap that appeared to cause variable issues. Changed it for a Bosch 1 235 522 060 Cap, (W113 Mercedes 6 cyl), which was much more secure on the distributor body. Also replaced the rotor with Bosch 1 234 332 024 for good measure. Now 3 years with no issues.

I love this distributor. But we shouldn’t have to spend $$$ for one then spend $ again to immediately replace the cap.

I recently bought a 123 distributor although the Lucas was still working. When I installed it I also installed a 1.5 Ohm Pertronix coil, since the distributor specs indicated it would work with anything over 1 Ohm. Initially it was hard to start the car but eventually I got it to idle and then took it for a test drive. I made it about 20 feet down the driveway and the engine died. I started it again and and it idles smoothly but when I started to drive away the engine died again. I put the original Lucas distributor and coil back in and the car ran perfectly. Swapping the 123 and Pertronix back in caused the engine to die when I accelerated. As an experiment I swapped in a 3 Ohm coil and the car ran fine. My conclusion is the either my 1.5 Ohm coil is bad or 123 really can’t handle the low impedance coil. So my question would be, what coil are you using?

I have two 123 distributors. A positive earth in a '62 and a negative earth in a '72. I run a 3ohm in the former and a 1ohm (ish) with original ballast in the latter - all standard. Both have been running faultlessly for nearly 10 years. I would stick to standard.

I doubt that this is a problem.

There’s lots of threads on problems with these things. If it runs well with your old dizzy why not start with that, then once you have everything else working you can come back to the 123.

Thanks Tim. I’ve wondered about that. I’ll check to see if that’s a problem.

Hi Steve. The 123 cap on mine was also crap. Loose fitting. I replaced it with a Bosch one as well. Much better, but still doesn’t fit as snugly as the original Lucas cap on the dizzy body.

Hi Mike, I was originally running an old coil (name long since gone) which tests at around 3ohm. I bought an Aeroflow XPro coil designed for electronic ignitions - tests at 0.9-1ohm. My 123 system idled and revved beautifully in the driveway, then played up (coughed and spluttered) after taking it for a drive. I’d stick to the old Lucas coil for a while, but that is worn. And it’s hurts to cough up big bucks for a new dizzy and not be able to use it.

Problem solved. Each time I swapped back to the old coil, it ran better, but the new coil tested ok (statically), so I wasn’t convinced. The distributor is fairly new and I replaced the cap supplied with a Bosch one (it fitted better). However, the central contact in the cap had fallen out - who knows where?! So the damaged cap handled the old coil output better than the new one. The new one, I’m guessing with much higher voltage, managed to make its own tracks to ground inside the distributor cap. Anyway - after putting the original 123 cap back on, everything is fine. :slightly_smiling_face: … for the time being at least. It is a Jag after all! :wink:

Here’s my post about the problems I had with my 123.

The central pin was laying inside the distributor. You can it in this photo.

Seems like you have more issues than I’ve had with my Mallory dual point set up … 1 condenser in 7000 miles and the points have zero wear

Hi Dave, Sounds like the same problem. I guess it all comes down to quality control. The cap supplied by 123Ignition was of poor quality (not a tight fit) and the Bosch one I replaced it with had the same problem as yours - the spring loaded contact falling out. I guess everything is made in China these days and there’s no choice on quality. Not sure where my pin ended up - probably on the driveway. I also found some vertical shaft play in my distributor which was remedied by some spacer washers on the shaft. Nor sure if this loaded up the central contact unnecessarily (through vibration).

I’m sure Roger’s dual point set up works wonderfully. I guess the attraction of the 123 setup with easy installation and a choice of timing curves is very desirable. Points always fail in the end. That said, you can’t knock it if it’s working for you.

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