12 replies to this topic

[petwar]

hi guys, ive bought this:





anyone tell me how to wire it in?

i know the back lights are missing but which way do the ignition live and the coil live go?

anyone???

[dklawson]

First a few suggestions:
See this FAQ at Speedy Cables: http://www.speedycab...page34aaaa.html
Use the search feature here for tachometer threads, there is a rear view wiring picture that is often posted and it will be of help.

Now onto a brief discussion. If you have electronic ignition, do not plan on using this gauge. Note the small print on the bottom of the face where it says "RVI". That means it's a current pulse sensing tach. It is NOT a modern tach like you are used to. The generally do not work with electronic ignitions. When you install them, they are wired IN SERIES with power to/through the coil. They do NOT use a single wire connection to the coil like a modern tach.

The Speedy Cables link is to an earlier version of your gauge. You'll notice on the picture link there that there is an external loop of white wire on the back of the gauge. On your gauge, that loop of wire is INTERNAL. So, instead of attaching a loop of wire to the back of your gauge, you will need two pieces of white wire with bullet connectors. One bullet will go between the back of the tach and coil (-), the other white wire with a bullet connector will go to the connector on the side of the distributor. Remove the existing white/black wire going between the coil and distributor. Now, current flowing through the coil will have to pass through the tachometer each time the points are closed. You need to connect an earth wire to the gauge case. That is typically done with a ring/eye terminal slipped over one of those threaded mounting studs on the back of the gauge. Lastly, you will need a switched 12V supply to the male spade lug that you see next to the two bullet connectors. That's it

Keep in mind (even if you have points and want to use this gauge) that the RVI tach is 40+ years old. There are components inside that fail. Unless the seller told you that this gauge was working last week, there's a possibility that it will have age related problems.

Good luck.

[petwar]

ah crap, thanks for that but im running electronic ignition i was looking forward to fitting that into the dash aswel!

[dklawson]

Sorry that this gauge won't work for you. Perhaps you can find someone wanting a tach (perhaps even someone on this board) who has a points ignition and sell this tach to them. That will free up some money for your next tach purchase.

For future reference, if you want a classic Smiths tach for use with electronic ignitions, look for ones with "RVC" on the face (primary donors being MGBs and MG Midgets). The RVC Smiths tachs use a single sensing wire connected to coil (-) and are very much like a modern tach. They will work with most electronic ignitions.

[petwar]

thats spot on mate, thanks!

[minituga]

can you guys help me wiring mine?

[GraemeC]

Ignition live to where the red wire is (standard colour would be white)
Connection to the -ve side of the coil where the black wire is (std colour wouold be white with a black trace) - do yourself a favour and re-crimp this connection if you plan to use the black wire.
Earth to the case. Looks like the original spade connection is snapped off so you'll have to connect to one of the threaded posts.

[minituga]

Ignition live to where the red wire is (standard colour would be white)
Connection to the -ve side of the coil where the black wire is (std colour wouold be white with a black trace) - do yourself a favour and re-crimp this connection if you plan to use the black wire.
Earth to the case. Looks like the original spade connection is snapped off so you'll have to connect to one of the threaded posts.

and being an RVC tacho woill this work on the Mini?
I heard something about a loop or something...

[GraemeC]

An RVC tacho will work on any ignition system. There are no loops for this type of tacho.

An RVI will NOT work on an electronic ignition system.

[minituga]

will test it tomorrow

[dklawson]

Follow Graeme's advice and wiring instructions.

As he said, you can't tell from the photographs whether the earth spade lug is snapped off the gauge case or not. If it is gone, just use a ring terminal on one of the gauge mounting threaded studs. by the way, the mounting studs are likely to have BA threads on them so I hope you still have the mounting hardware.

The gauge looks to be late MGB or more likely, from a Triumph circa 1976(ish).

[minituga]

didnt work...
probably the problem is in the tacho

[petwar]

hahaha, thats exactly the same one as i have now!