Emerald k3 & elderly Smith's tacho.

[Nigel Riches]

Well not off to a good start with this post, anyway, onto the reason for the entry. 

I have got the zetec running, under close supervision of an Emerald K3 ecu, all going well now, (thanks DW @ Emerald) but the 1982 vintage Smith's tacho doesn't want to have anything to do with the new boy in the engine bay, those piddling little signals from the ecu, not how a tacho expects to be treated. 

I have fiddled around with the "tacho multiplier"  setting but the instrument pointer still barely moves from the stop pin. 

So, over to the collective brain power of New BC, there must be someone out there who has encountered this problem. 

Short of biffing the tacho for a newer type, is there some way around this problem? 

Any ideas gratefully received. 

Regards, Nigel. 

[Mechanical Moz]

Is the tacho RVI or RVC type? It should be printed in small letters around the bottom of the face somewhere. RVI tachos generally won't work with anything electronic but can be converted to RVC with an add on board. Although I would think 1982 should be RVC you never know, worth a quick check.

[Bob_Rich]

Hi  Nigel

I designed a simple circuit that interfaces the Emerla ECU  withthe RVI  current triggered tacho. I fitted to my Elan +2 and it works fine.  It was detailed in a Club Lotus Mad acouple of years back . Will hapily send U a copy if You e-mail me. Would post it on this site  But dont know how to ! 

It is not complex but does require a small electronics circuit to be made up and fitted on the rear of the tacho and does not require any mods to a working RVI  tacho

hope this may help

Bob