14 replies to this topic

[Clubber Lang]

Does anyone know the best place to make connections for my new rev counter. The engine is an a series 1275 not a+
I was going to wire it to the coil as per instructions but it says something about not suitable on ballast resistor assisted starting? does this apply to mine? There is a small resistor or capacitor (as you can tell my electrical knowledge is limited) wired to the coil taking up the spare terminal. Just thought i would check on here before i start, regards Steve

[dklawson]

Can you quote the TIM instructions and/or scan and post them?

Generally there should be no issue using a voltage pulse sensing tachometer on a ballast ignition system as long as you are not also powering the tach from the coil connection.

The general rule for wiring aftermarket voltage sensing tachs is:
Black wire = Earth
Red wire = Switched, fused, 12V supply
Green wire = Sense (connected to the coil (-) terminal... the one with the wire going off to the distributor)
White wire = illumination
Some tachs also have a blue wire. Those are often used for an earth connection for the illumination bulb.

The coil (-) terminal will swing between 0V and +12V as the coil powers and discharges. This is true regardless of whether the coil/ignition is ballasted or not.

I suspect what TIM meant was that you cannot connect the red wire to coil (+) to supply it power on a ballast ignition system. Again, if you can quote the text and/or post a scanned copy that would help sort this out.

[RBAKER1275]

On my tim tacho (52mm) it is
Black = Earth
Red = Switched 12v (green with orange stripe in the later mini loom i think)
Orange = Lighting Positive feed
Green = Coil Trigger (black and white wire in loom)
I have a tim wiring diagram / instructions that i will dig out tomorrow for you, if you are still unsure.

[Clubber Lang]

The red wire it says can go to the coil but can also go to an ignition live? which could be where exactly? Also do i need to fit an inline fuse? what rating? thanks again Steve

[dklawson]

Thanks for the info on the TIM lighting wire color. That is different than most.

The suggestion in the instructions that the red wire CAN go to the coil (+) is what I was mentioning earlier as a reason TIM may have said not to use the gauge with a ballast ignition system. The ballast ignition system will not have enough voltage on coil (+) to power the tach's electronics.

Use their suggestion to connect the red wire to a switched 12V source. It doesn't have to be directly onto the ignition switch. The "green" wires in the loom are typically switched, fused 12V. If in doubt, use your car's wiring diagram to determine a green wire to tap into. I suggest that you do add an inline fuse to the red wire just to be safe.

[Clubber Lang]

Cheers guys, i did connect the red wire to the +on the coil and it seems to work o.k.? I suppose i can't tell how accurate it is though it seems fine with the speed of the engine. Thanks Steve

[RBAKER1275]

Tim Instructions, hope they help.

Attached Files

•  scan0001.jpg   1.36MB   63 downloads
•  scan0002.jpg   1.14MB   89 downloads

[dklawson]

RBaker, thank you for posting the TIM instructions. That is very helpful.

Clubber, it sounds like your tach is working OK. I don't remember your question about the ballast ignition system being answered. For future reference, this is easy to check if you have a multimeter. First, check the voltage you have across the battery terminals. It should be nominally 12.5V on a fully charged battery. Next, remove the distributor cap and place a coin between the points. (This insures current will be flowing through the coil when you measure its operating voltage). Switch on the ignition and measure the voltage from coil (+) to a good earthing point on the engine. If you measure the same 12.5V you measured on the battery, you have a standard ignition system. If you measure 6V to 9V, you have a ballast ignition system. Don't forget the remove the coin before you refit the distributor cap.

[Clubber Lang]

Cheers guys

[TiMtImInYtImTiM]

Sorry for resurrecting an old post but I need help fitting a Smiths 80mm rev counter. I purchased it second hand with no wires or instructions. 

[jaydee]

Old smiths..it can be either RVI or RVC which require two different wiring

Make sure it does work ok, i'm used to hook up a timing light to check them, i've seen some of these old gauges does not work and may give ignition issues

[dklawson]

As Jaydee said, there are two major types of Smiths electronic tachometers.  Please look at the face of your gauge for the letters RVI or RVC and post back with which you have.  If you can post a picture of the back, that would also help.  If you cannot post a picture, see if you can find a picture on the net that shows the back of a tach like yours.

 

Be advised that in general, RVI type tachs do not work with electronic ignitions. 

[nicklouse]

he has posted more info in this topic

 

http://www.theminifo...hs-gauge-wires/

[dklawson]

Thanks Nick.  I posted in the other thread requesting that TiMtImInYtImTiM find a picture online that matches the back of his gauge and post a link to that picture in the other thread.

 

TiMtImInYtImTiM, I think it would be better to post further correspondence on this topic in the thread that Nick posted the link to above.

[nicklouse]

To me it sounds like he has picked up an OE one as they are normally wired.

But without pictures of the actual item under discussion........