Electrics suppressor

[POP]

Hi,
I was taking the rev counter out to try and repair the clock and notice the small grey electrical fitting with a black wire just below the choke cable arm. The cable was not connected to anything. Is it a suppressor for the rev counter or radio and where should it connect to? I couldn’t see it on the wiring diagram but it looks like a factory fitting.
Thanks Pop

[MarekH]

It's just a capacitor. It is there to iron out any voltage spikes and provide a slow ramp up of voltage when the car starts. One side is connected to the 12v supply and the other side is earthed by connecting to the chassis.
kind regards
Marek

[POP]

Hi Marek,
Thanks for the reply. Is there a specific point it should be connected to on the supply. It only has a thin short cable,
Thanks Pop

[MarekH]

It has a thin short cable because it needs to go right next the thing it is protecting.
Given that it wasn't even connected and everything was still working, I wouldn't get too hung up about it. A rev counter working off of a points ignition would be a place where you expect voltage spikes - that's how they work.
kind regards
Marek

[christopher storey]

They were commonly fitted to the low tension side of the ignition circuit, and to the alternator, to suppress radio interference

[POP]

Thanks for the info guys. Given its probably not been connected for years and the car starts and runs ok, i think i will ignore it.
Kind regards Pop

[johnetype]

They were commonly fitted to the low tension side of the ignition circuit, and to the alternator, to suppress radio interference

and to the voltage regulator behind the central instrument panel which is where yours may well have started life.

They were associated with the fitting of a radio to suppress interference as Christopher says rather than with the build of the car. Given that many/most/nearly all? radios were fitted at the dealership not the factory, there would have been more variability in where they were fitted depending on the skill and diligence of the technician fitting the radio.

You don't need them if you haven't got a radio, the car will run fine with or without them.

[POP]

That’s helpful information John
Thanks Pop

[Series1 Stu]

Hi

Its true that your car will run fine without these suppressors and you won't notice if you don't have a radio fitted. Other people might notice though because you may be causing interference to their broadcast signal reception, which is actually illegal.

If you have suppressed HT leads or plug caps then that is usually enough for ignition generated RFI but sometimes your dynamo or alternator can be guilty of RFI and a suppressor needs to be fitted there. Sometimes windscreen wipers also cause interference, as can pretty much any motor driven item.

Regards