19 replies to this topic

[lippo]

 I've read many threads on the forum regarding the wiring an RVC rev counter into an aftermarket electronic ignition system and am still a little confused.  I managed to locate a very cheap RVC tacho locally and don't want to blow it up with wiring it incorrectly!

 

  I don't know what electronic ignition is fitted to my distributor and I hope this will be as easy as it was when I last did this to my Mayfair in 1990, whereby the black/white wire was already waiting to be connected to my tacho.

 

 So, am I right in thinking the spade terminal is to earth and the bullet goes to the -ve of my coil?

 

 

 

 

 Thanks for any help or pointers.

 

[Lplus]

The bullet and spade are not earth. IIRC there should be a white/black wire  and a lightgreen/orange wire free in the viciniity of the instrument cluster.  I think the white/black has a spade and the green/orange has a bullet female connector.  Those fit on the two insulated connections.

I seem to recall the earth is provided through the flexible printed circuit sheet which is fitted on the back of the instrument cluster and one of the earth paths fits under one of the screws in the back of the instrument.  You will need a three instrument flexible printed circuit sheet to fit the existing two instruments and the rev counter into the three instrument cluster.  The mounting bracket to the car is also different for the three clocks

 

The coil wiring should not need to be changed.

 

by the way, the uninsulated connection to the  distributor should be taped over.

 

I'd have to dismantle mine to recheck this for  absolute accuracy so proceed with caution.  Hopefully others will chime in if I've got it wrong.

[lippo]

 Thanks Lplus, you may have saved me a cooked tacho. I'll look exactly where the earth needs to go, I don't think my current 2 clock dash will have the additional circuit sheet for the tacho.

[timmy850]

All you need to know is in here:

https://www.triumphc...pdfs/Smiths.pdf

[Lplus]

 Thanks Lplus, you may have saved me a cooked tacho. I'll look exactly where the earth needs to go, I don't think my current 2 clock dash will have the additional circuit sheet for the tacho.

No, it won't, but minispares sell them. I'm assuming that the speedo and guages are smiths as well.  I don't know if you can mix smiths and japanese instruments. (I suspect you can't) The bracketry to fit the cluster to the car might need to be sourced second hand.  part no CZH245.

[lippo]

All you need to know is in here:

https://www.triumphc...pdfs/Smiths.pdf

 Thanks Timmy, very informative and has the simple wiring diagram I was looking for.

 

 

 Thanks Lplus, you may have saved me a cooked tacho. I'll look exactly where the earth needs to go, I don't think my current 2 clock dash will have the additional circuit sheet for the tacho.

No, it won't, but minispares sell them. I'm assuming that the speedo and guages are smiths as well.  I don't know if you can mix smiths and japanese instruments. (I suspect you can't) The bracketry to fit the cluster to the car might need to be sourced second hand.  part no CZH245.

 

 Thanks Lplus, I'm using my original speedo/fuel water temp dash and adding the original (noe Japanese I think) tacho. I did need to make some minor alterations to the case as it was a little ******* eyed and about 5 degrees out when fitted on the 3 clock binnacle but the case wasn't the original case as that had been cracked beyond use. Seems fine now. I have already purchased the 3 clock frame for the cluster to bulkhead, was about £25 from eBay.

[Verderad]

This is the back of my 3 clock cluster 

I have another pic that shows fixing of black wire into the regulator and tach willl post 

Edited by Verderad, 29 May 2024 - 09:04 PM.

[lippo]

 Thanks Verderad, that's very useful. I won't buy a new printed circuit sheet just yet, I should be able to wire it up temporarily for now. I'm missing the little brass bolt that goes into the case in between the bullet connector and the bulb holder (yours looks like a mini capacitor?) I think I have the info regarding the bullet and spade connectors and where they go to in the engine bay too.

 

 Looking more closely at yours, it seems different to the other PCB's I've seen, specifically the black wire from the voltage regulator to the tacho, if you do have another photo, that would be handy. This is the wiring I've seen so far;

 

[GraemeC]

The black wire is an earth and on Ian's is probably going to a spade connector that's screwed to the tacho.  The later blue PCB doesn't need this as the PCB provides the earth link (the copper pad under the screw, next to the lamp).

 

You don't need the PCB - everything on the tacho could be connected with wires, you'd just need to get handy with a soldering iron if you wanted the illumination to work.

[lippo]

 

 

by the way, the uninsulated connection to the  distributor should be taped over.

 

 Which one is this?

[lippo]

The black wire is an earth and on Ian's is probably going to a spade connector that's screwed to the tacho.  The later blue PCB doesn't need this as the PCB provides the earth link (the copper pad under the screw, next to the lamp).

 

You don't need the PCB - everything on the tacho could be connected with wires, you'd just need to get handy with a soldering iron if you wanted the illumination to work.

 Soldering iron at the ready. Plus, I'm not spending £60+ on a replacement PCB.

[Lplus]

 

 

 

by the way, the uninsulated connection to the  distributor should be taped over.

 

 Which one is this?

 

The other end of the short white wire with a blue cover plugged into the coil negative.

[lippo]

 I've taken the 2 clock cluster out and thankfully there's a white/black wire with a bullet connector at the end. Looking at the wiring diagrams, I need a light green/orange wire to connect to, I think there may be one in the loom that I can take a feed off. Looking at the wiring diagram, the LG/O wire goes all over the place.

[GraemeC]

LGO is a fused live feed from the second position (ACC) of the ignition switch. There should be plenty of them around

[lippo]

 I've installed the tacho and connected it up but no joy with it working.

 

 I have taken a +ve feed off the LGO wire into the dash connector - it correctly registers 12v when key is in second position.

 

 I have taken an earth to various parts of the body as a temporary connection, including the body itself.

 

 I have made sure the (pulse) bullet connector is connected to the -ve of the coil. 

 

 I have measured the voltage between the (pulse) bullet connector and the +ve off the LGO wire and there is a constant 12v. Is this correct?

 

 I do have aftermarket electronic ignition for which I have no information. There was a disconnected black/white wire from the loom near to the distributor/coil but connecting that made no difference, there is 12v running to the bullet connector whether this is connected or not.

 

 Any advice or thoughts would be appreciated. The tacho could be knackered for all I know, it seems strange that there's a constant 12v though.

 

 

Edited by lippo, 31 May 2024 - 02:17 PM.