4 replies to this topic

[G_A_C89]

Hello everyone,

I brought a smiths tachometer off eBay a few days ago thinking it was going to be a piece of cake to fit. How wrong was I (or am I just an idiot)
I have been looking on the forum everywhere but all I come across is either after market tachos or tachos that don't have the same wiring that my one has.

WARNING: you will have to explain how to fit it like you're talking to a 5 year old as I'm not very good with this wire malarkey.

Here are some pics of it, if that helps.

on the front it says (RPM x100) (4 CYL Negative earth) RVI 1413/01









Any advise will be greatly appreciated!

Edited by G_A_C89, 30 January 2008 - 05:13 PM.

[morley]

I'm not sure of is this is of much help:

[Guess-Works.com]

If you have electronic ignition, then forget it....

but basically the pictures above are about right....

However... do a search or just look under DKLawson's posts and you'll find all the information you need...

[dklawson]

I do seem to post a lot on Smiths tachs.

As GuessWorks said, if you have electronic ignition... forget using this tach. What you bought is called a Smiths RVI tachometer. It senses pulses in the current flowing to the coil as the ignition fires. These were phased out in the early 1970s. They never liked working with electronic ignitions and they are now approaching 40 years old. Capacitors don't last forever.

If you have points ignition, the picture posted above explains the wiring well. Summarizing: switched 12V power in, case connected to good earth/ground, and then there is the induction loop which goes between the dizzy and the low side of the coil (replacing the black/white wire that normally makes this connection). If the tach works but is erratic, swap the connection points of the white wires (coil to dizzy, dizzy to coil). This will reverse the direction of current flow through the loop on the back of the tach. Some people have reported that creating a second loop on the back of the tach sometimes helps. I have no first hand experience with this... I'm only passing along hearsay.

by the way, since most of the RVI tachs were made before 1972... pay close attention to any polarity notations on the gauge and/or its face. A lot of these were positive ground instruments.

[G_A_C89]

I do seem to post a lot on Smiths tachs.

As GuessWorks said, if you have electronic ignition... forget using this tach. What you bought is called a Smiths RVI tachometer. It senses pulses in the current flowing to the coil as the ignition fires. These were phased out in the early 1970s. They never liked working with electronic ignitions and they are now approaching 40 years old. Capacitors don't last forever.

If you have points ignition, the picture posted above explains the wiring well. Summarizing: switched 12V power in, case connected to good earth/ground, and then there is the induction loop which goes between the dizzy and the low side of the coil (replacing the black/white wire that normally makes this connection). If the tach works but is erratic, swap the connection points of the white wires (coil to dizzy, dizzy to coil). This will reverse the direction of current flow through the loop on the back of the tach. Some people have reported that creating a second loop on the back of the tach sometimes helps. I have no first hand experience with this... I'm only passing along hearsay.

by the way, since most of the RVI tachs were made before 1972... pay close attention to any polarity notations on the gauge and/or its face. A lot of these were positive ground instruments.

Thanks dklawson and everyone, however I have one question well it’s a few actually.
Firstly in the pink smiths diagram above there seems to be a few more wires than my tacho, which is really confusing me because it’s still not clear which terminals I have to link up to and where. So dklawson as you are a genius and the knower of all, would it be possible to tell me what links what. oh and its still got its points non of that electronic stuff : )

I have labelled what I think is correct but it’s probably wrong so if anyone want's to join in and help me with my quest feel free! Thanks again for your answers.

Edited by G_A_C89, 30 January 2008 - 05:44 PM.