Sorry, only just picked up on this thread. Nice work on those gauges chaps, they look superb.

Re the 4 to 6 conversion, yes, as JR mentioned, I used to do them, but that external box John spotted looks a lot easier! My mod involved uncasing the tacho, replacing the old electronics with new, then recalibrating, and as JR also noted, the input circuitry needed tweaking depending on if it was coil or ECU driven.

I think I might have one or two of the PCBs left if anyone wants to DIY, but if I do, they are bare boards and I don’t have the components in stock.

If anyone is desperate, I’ll help if I can, but I’m not ‘offering a service’ as it were.

One note, if you happen to be using an aftermarket ECU, it’ll almost certainly have a built-in tacho conversion feature allowing you to use a stock 4 cylinder tacho.