13 replies to this topic

[[email protected]]

I recently installed ('87 Mini w/1380)  a Clubman GT (I assume that's the origin) 3-clock set with a Nippon Sieke rev counter. Wired correctly, I believe, with the wires already in the loom (Green/orange-spade provides "+" power, white/black-bullet "- earth" pulses - I think.).  The rev counter shows about twice (?) the engine speed - ex.  about 4,000rpm shows about 8000rpm.  I have a Pertronix electronic ignition installed and wonder if this could be causing this problem? 

 

My theory/question:  Since the rev counter gets its input from the coil negative, and the dizzy rotates twice for each "4-cycle" rev, could the rev counter be picking up both pulses for each "cycle"?   No doubt the rev counter must be built to account for the 2-pulses per "cycle".  Is it likely that the electronic ignition is confusing it, and if so, is there a way to "calibrate" the rev counter?  No way I'd give up the Pertronix ignition - the best thing ever invented for classic British cars.  If it's not the Pertronix, is there another way to pick up the engine revs that might eliminate the problem?  

 

What else could cause this problem?

 

Is there some kind of electronic gadget that can halve the pulses it passes through?  Since these are from the coil negative, they are "earth" pulses I presume? 

 

Any suggestions will be greatly appreciated...

 

[dklawson]

I have no first hand experience with the later Nipon Seiki gauges.  However, I have seen several threads on this board that talk about very late gauge clusters from the injected cars not being fully compatible with the early cars since the later gauge pack connects to the ECU instead of the coil.  I remember the error being a factor of two but I don't remember if this was a factor of two higher... or lower.  Hopefully others familiar with the later injected car gauges will post soon.

[KernowCooper]

Usually when you see a 3 dial rev counter reading twice engine revs it when the 3 dial dash came from a later car with a coil pack ignition MPi, where the later cars wiring picks up the rev counter feed from 1 coil pack only, if yours is from the later car then there is a mod listed here somewhere to get the tacho fixed.

[RedRuby]

If you have a MPi Rev counter have a read of the attached document it tells you how to calibrate it for a non MPi model

http://www.theminifo...attach_id=91384

[Spider]

If you have a MPi Rev counter have a read of the attached document it tells you how to calibrate it for a non MPi model

http://www.theminifo...attach_id=91384

 

That's a great guide for sure, how simple is that.

 

Can I suggest though as it is a variable re-calibration, doing it this way;-

 

If you can get your hands on a 12V AC Transformer, a Plug Pak type will be OK, but HAS to be AC, not the usual DC, ones

 

Power up the Tacho in the normal way with 12V DC and connect the 12V AC between Earth and the 'Points' connection. If your Power at home is 50Hz AC, the adjust the Tacho to read bang on 3000 RPM.

 

If it's 60 Hz then adjust it to read 3600 RPM.

[[email protected]]

 

If you have a MPi Rev counter have a read of the attached document it tells you how to calibrate it for a non MPi model

http://www.theminifo...attach_id=91384

 

 

 

If you have a MPi Rev counter have a read of the attached document it tells you how to calibrate it for a non MPi model

http://www.theminifo...attach_id=91384

 

That's a great guide for sure, how simple is that.

 

Can I suggest though as it is a variable re-calibration, doing it this way;-

 

If you can get your hands on a 12V AC Transformer, a Plug Pak type will be OK, but HAS to be AC, not the usual DC, ones

 

Power up the Tacho in the normal way with 12V DC and connect the 12V AC between Earth and the 'Points' connection. If your Power at home is 50Hz AC, the adjust the Tacho to read bang on 3000 RPM.

 

If it's 60 Hz then adjust it to read 3600 RPM.

 

 

 

Wow, you folks are great!  Talk about a storehouse of Mini knowledge.  I did not know that the MPI tacho is different, and it does sound like that is likely the problem.  But I was told that the 3-clock cluster I have came from a Clubman GT - so is there an "easy" way, by looking at it, to tell if the tacho is from an MPI, or must I disassemble it (and the dash to get at it)  to see if it has the variable resistor, etc?  The article that you referred me to is exactly what I needed if the tacho is from an MPI.  And thank you for the terrific idea for calibrating with a 12V AC (60hz here in the USA) transformer.  

 

Other suggestions/possibilities?

[[email protected]]

Just an FYI - for the purpose of finding out if this is an MPI tacho, the speedo in the 3-clock set is in MPH.  Did the MPI models still use MPH speedos?  I had the impression that they were in KPH.  Does this MPH speedo make it less likely that the tacho is from an MPI model?  The reason I ask is that I have a full wood 3-clock dash with 3 auxiliary gauges, a "complicated" sound system, modified air vents, etc, and it was a devil to get it installed with everything working.  Maybe the memory is still too recent...thus the reluctance to disassemble unless absolutely necessary (but, of course, I will if I must!). 

 

Thank you again for your valuable assistance.

[GraemeC]

Plenty of MPi cars with mph speedo heads - their home market was the UK.

Nippon Seiki dials were never used in the Clubman and GT

[Fast Ivan]

post a pic up and we'll know for sure what it is you have, does sound like MPI clocks though

[[email protected]]

Plenty of MPi cars with mph speedo heads - their home market was the UK.

Nippon Seiki dials were never used in the Clubman and GT

 

 

post a pic up and we'll know for sure what it is you have, does sound like MPI clocks though

 

This forum is great for learning the intricacies and details that never come to mind until you encounter a new problem.  viz. the Nippon Seiki dials were never used in the Clubman and GT.  So they're a later 3-dial version (though I was told they were from a Clubman).  And the MPI did use MPH.  I'd certainly never know these things by chance!  Anyway, I have no doubt that they're MPi gauges and will do "the fix" as soon as I can (too many other projects...)   I'll post the results.  Thank you all again!

Edited by [email protected], 23 June 2015 - 12:06 AM.

[Spider]

 

This forum is great for learning the intricacies and details that never come to mind until you encounter a new problem. 

 

 

For a car which from the outside appearance was little changed over it's 41 year production life, there was very few (if any!) parts that were not changed / up graded / modified / improved / made worse from start to finish!

[spiguy]

Usually made worse!

[[email protected]]

Reporting back as promised.  Removed the dash and fixed the tacho by following the excellent tutorial you steered me to.  Calibrated it with another electronic rev counter wired with jumpers to the same terminals.  I was pleasantly surprise by how easily the dash re-installed.  Everything must have been settled (crushed) into place the first time.

 

I'd post a photo of the calibration set-up, but I can't figure out how to imbed a the image.

 

I will happily mark this problem as "solved", thanks to the excellent help from you great Mini fanatics    Much appreciated. 

[gazza82]

 

 

I'd post a photo of the calibration set-up, but I can't figure out how to imbed a the image.

 

 

 

Upload any images to a photo website such as photobucket ... http://s1315.photobucket.com/... you will need to create an account. Then follow the instructions to upload your pictures. Click in the link to your pic in the menu on the right, and click on the small image button on the menu bar of the post you are creating and paste the link in ... voila!

 

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