S3 E Type tachometer

E-Type
1

Just wondering if anyone has had this issue with their rev counter. Mine operates normally, but at approximately 3200 rpm the needle stops dead. It is as though there is a pin poking through the face and the needle hits it and stops. Any clues as to what may cause this?

Thanks in advance.
Regards.

2

Hi Chris,
Welcome to the forum, I’m not an electronics expert so I can’t really say why your tach is acting that way but I would be looking at sending it off to have it fixed. I’ve used both Nissongers and MoMa with good results. MoMa was a bit cheaper and faster IIRC.
Good luck,
Cheers,
LLynn

3

Thanks LLynn, appreciate your reply. Might have to follow your advise and get it looked at; just thought there might be a simple “look-as-this…” as this is an impulse rev counter attached to the OPUS unit…

Regards,
Chris

4

Chris

Rather first spend money on getting rid of the OPUS ignition. It might be electronic but its not a good system, both in terms of design and specially now - after 50 odd years - reliability. Its only a matter of time before it leaves you by the road side.

Your options are:

  1. fit the Lucas AB14 ignition system from an HE V12, complete with dissy and DUAL coil setup. This may be the the cheapest conversion (if you can find a system) and would include vacuum advance that would bring at least a 20% fuel consumption benefit on the open road. Its also standard Jaguar parts. (The vacuum retard module is a most unfortunate leftover of early 70’s attempts at meeting the emissions specs at the time.)
  2. Lumenition has a fool proof, plug and play solution, with an “installation kit” specifically for the OPUS dissy. I have this on my S3 and it works very well up to 6000rpm. I also recommend that you also upgrade the vacuum retard module on the dissy to a vacuum advance (JLM519) for the fuel consumption gains mentioned above.
  3. I’ve read that Pertronics is also used by I have no experience on this option. Again the vacuum advance upgrade would leave you very pleased.
  4. SNG has an OPUS look alike modern system but the dissy they supply also comes with the vacuum retard module - again it would be much better to rather implement vacuum advance.

If you then still have the tach problem, then spend money on that. I’m not implying that the OPUS is the cause of the tach problem.

5

Hi Philip,
Thanks for your response, a lot of really good information. I have done a bit of research on the OPUS unit, and while my engine number is well after the “Mk 2” version introduction am well aware that the unit was not “perfect” by any stretch of the imagination. Am aware the inventor/developer of the OPUS unit made, in his retirement, a “new improved version” to satisfy grumpy customers, but he has now ceased all manufacture due to the fact he is now over 70 years of age.

Your suggestions give me something concrete to follow up. Am aware of the SNG solution, but that was not a cheap option considering it is module, distributor, ballast, and coils; plus an exchange fee.

I like the idea of the Lucas conversion from HE V12, particularly as where I live a lot of car wrecking goes on so there may be opportunities… Looks like your list 1 --> 4 will be the order I will investigate. It might also solve my cold starting issues as well…

Thanks again,
Regards,
Chris

6

Hi Chris, Before you throw lots of cash at it, I would suggest that that you check the gauge internals to see if something internally is impeding the mechanism. A piece shaken loose, vagrant insect…who knows what a bit of debris might cause.

7

Chris, in case of implementing the Lucas system, remember to take BOTH coils. That 2nd coil (Auxiliary coil with the blocked off HT port) is very important since that is the one that ensures good spark above 4k rpm.

Other than healthy spark, the cold start enrichment system (aka Choke) must work and correctly so. Too much enrichment and you may have issues, too little, ditto.

On my car I find when its “cold” (ie less than ±15degC) I need to pull the choke lever to the 3rd detent, and as soon as she fires, push in to the 2nd detent to avoid overfuelling. Then, less than 1km later, push to 0.

8

Another option is MSD 6A with Crane optical pick up. Simple, easy to install and reasonable. I ve had it for 20 years…

As to the tach it could indeed be an issue with the signal rather than the tach. Call Nissonger maybe they have seen the symptoms. I ve never had to mess with my tach although I had it rebuilt along with the other gauge during the recent restoration

9

OK, I’ll say it:

Don’t forget an EDIS set-up

Craig

10

Thanks John, good thinking.

11

Thanks Philip,
Am sorting out part numbers of what is required, and a wiring diagram. Am picking that the wiring harness on the HE will accommodate the extra coil but will have to add additional wiring to the E Type to connect everything up…

12

Thanks Craig, but might be a bit too clever for me…

13

Dumped my Opus years ago for Crane although possibly no longer made. Seem to remember it had to come off the coil.
Issue is my rev counter has died some years later and having sent it off to Speedograph Richfield for repair I was today told it’s a knackered chip and they’ve put in uprated internals. Get it back next week. Probably old age like my speedo was also recently.