27 replies to this topic

[dklawson]

Raul, I did not ask you this earlier but should have.  Does your car have electronic ignition?

[RaulSims]

Raul, I did not ask you this earlier but should have.  Does your car have electronic ignition?

No, it does not. It is the standard distributor kind (points ignition, i think this is the term).

[RaulSims]

Can any one please help ?

[Spider]

On the back of the Tach, there maybe a rubber plug (depending on the model), if you remove that, there should be some small DIP type switches inside.

 

If there are 6 Switches, they need to be slected;-

 

Switch 1 needs to be OFF

Switch 2     OFF

Switch 3     ON

Switch 4     OFF

Switch 5     ON

Switch 6     OFF

 

That will program it for 4 cylinder with Points type Ignition system.

 

 

If there are 2 Switches (and I suspect this is what you have), they need to be configured;-

 

Switch 1    OFF

Switch 2    OFF 

Edited by Moke Spider, 16 July 2015 - 10:36 AM.

[dklawson]

Raul, Spider's information is relative to the "new"/modern tachs made by Caerbont and marketed under the Smiths name.  If your gauge has two bullet connectors, it is not this type of modern tach.  The modern Smiths tachs will have multiple colored wires coming out the back without bullet connectors.

[RaulSims]

Hi, thank you for the answers. The back of my gauge is like this:

 

It is working, but reading with about 50% error. Is there any way to fix it ?

 

Thanks in advance.

[dklawson]

That is an early style RVI tach with the external induction loop.  The block with the brass thumb nut receives a loop of wire that goes in series with the wiring going to the coil.

 

Some additional information is in the link below to general wiring of these gauges:

Smiths Impulse Tach Wiring PDF

 

Make sure your wiring matches what is shown in the PDF.  Beyond that I am not sure if there are provisions for calibration and/or cylinder count on this tach.  You may find a trim-pot or dial switch under the rubber grommet on the back.  The trim-pot would be used for calibration.

[RaulSims]

That is an early style RVI tach with the external induction loop.  The block with the brass thumb nut receives a loop of wire that goes in series with the wiring going to the coil.

 

Some additional information is in the link below to general wiring of these gauges:

Smiths Impulse Tach Wiring PDF

 

Make sure your wiring matches what is shown in the PDF.  Beyond that I am not sure if there are provisions for calibration and/or cylinder count on this tach.  You may find a trim-pot or dial switch under the rubber grommet on the back.  The trim-pot would be used for calibration.

I tried to go to the link but this message was shown "Permission denied: links to files in the forum are only allowed from this web site."

 

Could you please attach here the pdf? Thanks once again for the help.

[dklawson]

Sorry about the link.  The link is to the MG Experience web site so I do not have the PDF to send you.  I can try posting a link to the MG Experience posting.  Perhaps that will let you see the document.

 

The link below is to the MG Experience thread

http://www.mgexp.com....php?71,2439530

 

The link below is to a similar document on the Mk1 Performance web site:

http://mk1-performan...pulse_tacho.pdf

 

and again in the link below

http://www.magical.e.../Tachometer.pdf

[RaulSims]

Thank you, the links worked fine. The wiring is correct. When you say "You may find a trim-pot or dial switch under the rubber grommet on the back.  The trim-pot would be used for calibration." are you refering to the black rubber on the back that is seen on the picture that i've posted?

 

Regards!

[dklawson]

Yes, I was referring to the plug on the back of the tach.  I don't know for sure what is under there but it may be a potentiometer to adjust the calibration.

[RaulSims]

Yes, I was referring to the plug on the back of the tach.  I don't know for sure what is under there but it may be a potentiometer to adjust the calibration.

 

Thanks, i guess i will find out ;)

[dklawson]

If this does not work out, I suggest you start a new thread.  Your inquiry piggy-backed onto an older thread that is marked as solved.  Starting a new thread will get some fresh eyes on the issue.