Tacho for a 1956 Citroen

[Julian B]

I would like to retro-fit a small (~52mm) tacho to my 1956 Citroen, but have not found much help with their forums to date.

The car has a 6v system, with a dynamo, distributor, coil, and 4 cylinders; "red line" is 4,000rpm, none of which would I want to change. But my knowledge of elektrickery is limited ...

I can't find a 6v 52mm gauge with a sensible scale (ie 4-5,000), but would this 12v gauge work
https://www.ebay.co.uk/itm/Tachometer-0 ... SwFL9TvCzF

... if I also wired in this converter?
https://www.digital-speedos.co.uk/acces ... auges-p338

The eBay advert describes it as suitable for "alternator or ignition coil"; does having a dynamo & ignition coil cause a problem?

Would the 6-12v Conversion unit put any undue stress on the electrical system?

I rarely push the engine hard, and doubt I ever get anywhere close to 4,000rpm, so I would hope that this scale is suitable.

Thoughts?

TIA

[AustHaflinger]

Well I can follow your logic and if the converter is placed between switched 6v on the car and the switched 12v input side of the tach that should work.

The only concern is the coil ignition side where the tach gets its ignition pulse - to over simplify this is 6v energising the ignition coil from the distributor - now as this goes through the coil I am not sure what it does to the 6v - now the tach needs the pulse but I am not sure what voltage it needs to see - 12v or its does not matter. I suspect you may need another converter on the tach ignition pulse side as well - but will it be able to respond quickly enough to the 6v pulses from the coil, if not the tach may just see a steady 12v instead of a pulsed signal.

You can only try.

What I would do is buy your tach and one converter - and wire it up with the converter on the switched 6v power side. Connect the pulse feed to the tach from the coil and see what happens. If it does not work get a 12v battery to replace the converter and move the converter to the ignition pulse circuit and see if it works. If it does work buy a second converter to replace the 12v battery. Clear as mud -lol

I guess you cannot find a 6v tacho - some bikes and aftermarket VW may suit.

[heinkeljb]

Julian,
I have a cheap 12 volt Tacho you can borrow to just put on and see if it wokrks as is before you buy anything. If the gauge really does require 12 volts then I can provide a small seal 12 volt battery that can be use to see if the signals pulse is sufficient for the hushed to work. If it works, then you can buy the converter to see if that works instead of the battery.
If it require a better pulse then we can see what other options like using the converter we need to make it work.

John

[Julian B]

Thanks John - I'd like to take you up on that

No rush whatsoever, but could pop down most evenings (or even this afternoon if convenient / to hand). Just let me know what works for you.

Julian

[AustHaflinger]

An old thread - in looking for instruments for other vehicles I came across this company in the US https://www.speedhut.com/

They can provide virtually whatever you want (you can basically design your own instruments) and their tachos will run on 2 cylinders up.

Garry

[Julian B]

Thanks Garry - as it happens I had one made in the US only a month ago, and have now fitted it. Not cheap - but not dissimilar to your link, and works perfectly.

http://www.westach.com/products/6%20VOL ... /index.php

For my Haflinger I bought a VDO gauge (#333-968) - looks right aesthetically, but I do wish the top RPM was 5k or 6k, rather than the 8,000 it displays.

[pureredcordial]

Or have a look at marine tachometers....multi voltage, 6000rpm range, and very programmable as to number of pulses per rpm
eg https://www.ebay.com.au/itm/Marine-Car- ... rk:11:pf:0

[pureredcordial]

Oh that one only goes down to 9v but there may be others