Tach Oscillation and Mystery Switch

[surfguitar58]

Went to my first “Lotus event” yesterday (New England Lotus Lovers Inc. or “NELLI” start-your-engines gathering.) Other than being the only Europa in attendance out of about 10 cars, it was lots of fun.

This was also my first real drive of more than a few miles in this (or any) Europa, AND IT WAS GREAT! (But you all already knew that.)

As I am sure will happen every time I pull out of the driveway, a few issues have cropped up that I am hoping the experts can help me out with:

1 – My tach needle hunts (wobbles, varies, oscillates) +/- 500 to 1000 RPM at anything above idle. I think I have the stock ignition system, but possibly a new coil, and there is a dangling, disconnected wire (one of many throughout the car) next to the coil. Don’t know if these are related, but just wondering if this is an easily diagnosed problem before I start tearing the dashboard apart.

2 – My deceased PO seems to have installed a toggle switch under the dash on the passenger side, next to the center console. It does not appear to be a kill switch as it did nothing when activated with the engine running. It did make the tach needle jump briefly when activated, so it is doing something, but nothing exploded, and I was not ejected out of the car James Bond style as I feared. Just wondering if this is some common aftermarket fix that everyone has, but that I was unaware of.

Thank you for indulging my newbie exuberance, and advice would be greatly appreciated.

Tom

[Grumblebuns]

Hey Tom, from the picture, it looks like you're stuffed into the cockpit  , not much room left over. Car looks really good, congratulations on getting it on the road.

[BDA]

Congratulations on getting your car on the road!  As well as getting into the car! 

Actually, I can relate because people are almost as interested in watching me get into my car as the car itself.

That sounds like it was a fun event!

As for your tach issue, my guess is that it's ignition related. Find out exactly what sort of ignition you are running. If you're running points and condensor, then the problem is in your tach. If you're running a Pertronix or other more modern ignition, I believe there is a documented fix for the tach that will fix it.

My engine came with a light triggered ignition and the (stock) tach would bounce pretty wildly above a few thousand rpm. When that ignition failed, I replaced it with a Pertronix and the tach started behaving itself! I have no explanation for that as that is counter to most people's experience. Since I think the Pertronix is superior to points and condensor, I might try installing the Pertronix, including the coil (make sure you have resistance wires) and see if you get as lucky as I did. If you aren't, then a speedo shop or Nisonger would be my next move.

It's not out of the question that somebody here knows how to fix the tach and that may be the easiest option.

Good luck!

[Roger]

I have Pertronix on Elan and Europa TC, thoroughly recommend it.
To fix your tach, with Pertronix or other electronic triggering, contact Spiyda in the UK. No, that's not a spelling mistake! They make a very inexpensive, easy to install, conversion that fixes the problem. Around 40GBP  plus shipping.  www.spiyda.com

[surfguitar58]

Hey Tom, from the picture, it looks like you're stuffed into the cockpit  , not much room left over.

Not sure what all the fuss is about getting in and out of the car. I simply cover my entire body in lube and have 3 friends stuff me into the doorway. Eventually I pop right in! 

[surfguitar58]

Thanks for the advice BDA and Roger; I have a Pertronix distributor, coil and wires that came with the car un-installed, and on my to-do list to install them. Before the current tach situation came to light I was in contact with Nisonger (Smiths service company, apparently the US version of Spyida) about compatibility of the Pertronix and they insist changes absolutely need to be made to the stock Smiths tach to work with electronic ignition, BDA's experience not withstanding. I'll investigate what ignition system I have currently and report back.
Tom

[4129R]

The mystery switch may be a fan thermostat overide, which just earths the rad fan motor when the thermostat does not do the same.

Quite useful to stop the engine overheating in traffic when the otter switch dos not earth properly.