The old Lucas 45D4 distributor was doing a good job from 2000rpm and up, but the timing was too advanced at idle, making starting difficult. It could be altered to make it better: build a distributor testing machine, dismantle the distributor, make new springs, change the advance weights, test and test and test again until it’s right… or I could buy a modern digital distributor.
123ignition make few drop-in replacements. The basic model has 14 pre-set advance curves to choose from, and once set is ready to go. Other models are programmable over USB or even Bluetooth. The programmable models sounded good, but 123ignition made it clear they would never release an API or even document the communication protocols, even if the company went under. I’m old enough to have owned devices which became paperweights when the app that ran them was no longer available, and I’d prefer not to risk that with my classic car’s engine.
So I went with the pre-programmed model, the 123/MINI-R-V.
Mmm, shiny. The handbook comes with a chart of the 14 different curves, and you select a curve using the rotary switch:
In my case curve E matched the existing distributor’s curve from 2000rpm and up, but had the correct advance at idle too. Perfect! It was installed and the engine started right up, a bit of tweaking to get the timing spot on, and that was it.
However… the 123ignition distributor cap is even less waterproof than the old Lucas 45D4, which is quite a remarkable feat. The Lucas distributor has an extra flange where the distributor cap meets the body, forming a reasonable seal. The 123 has a large, thirsty gap. Not a problem on a sensibly-designed car, but not great on a Mini where the distributor sits up against the grille.
I’ve designed and 3D printed a water deflector/seal that slips onto the 123 distributor body and fits closely to the distributor cap. The seal has an internal air gap and drain channels to let any water escape. Sealing could be further improved with some silicone grease between the seal and distributor cap, but I haven’t needed it yet.
I’ve published the design on Thingiverse here so anyone can print one of their own out of flexible TPU rubber filament.