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white wires to my tac?

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Sopwith_Camel

Sopwith_Camel

Jedi Knight
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hi I am putting together a 73 midget I bought in boxes. yes I hear you laugh. and Im puting in a 67 dash. stop laughing.
so I have one white with black tracer that comes up from the coil. it should plug in to the back of the tac I have switched the tach to neg earth. I have the white with black doing its little loop on the back of the tac, but where dose it go from there? I dont have the other white wire on my 72 I have a white wire that gose in to the back of the tac and one that comes out with specail conectors. but not on the 73.
shouldent the wire go back down to the coil or distributer?
to make matters worse I put in an "igninter" so I have a red and black wires coming out of the destributer.
Hellllllllp!
 
The white wire goes...........
From the ignition switch through the tach (loop) In and out on your tach via those connectors. And to the positive side of the coil.
The 73 tach was different, it recieved it's signal from the neg side of the coil not the internal loop like the 72.
If you only have the one bullet connector on the tach, hook it to the - side of the coil.
If you have 2 bullets, 1 male, 1 female, run a wire from the key in one of those bullets, back out the other and to the + side of the coil.
 
Normally the white w/black tracer is the wire from the distributor to the coil. There should be a white wire that goes from the coil to the back of the tach (loop thing) and from there to the ignition on switch pole. Also a '73 Midget was from the factory negative ground, so did you convert a earlier postive ground tach?
 
yes I did convert to neg ground. the white w/Black tracer enters the harnes by the coil and exits by the tac with a female bullet. there is a white w/black that enters and exits right by the coil that use to connect the distribluer to the coil. but now I have the "igniter" and a soild red and solid black. the two resonces are makeing this clearer to me. so I take a white from the key up to the tac around the loop and down to the positive side of the coil.
 
So you have Pertronix now? Do not spend any more time with the RVI tach (the one with the looped wire on the back). RVI tachs are hit-and-miss with electronic ignitions. There are more stories of failures and problems when these are used with Pertronix than there are stories of success.

As others have mentioned the later tachs were different and that's what you want for the Pertronix. Look for a tach with RVC on the face. Those are voltage sensing. They have a single signal wire connection to coil (-) and they work with electronic ignitions.

There are a number of articles on the web (including mine) that discuss tach conversions. Some people transplant the RVC movement into an RVI case where original appearance is important. There are also a couple of companies and individuals who make circuit boards to convert the earlier (RVI=current sensing) tachs to operate like later (RVC=voltage sensing) tachs.
https://home.mindspring.com/~purlawson/files/Smiths%20Tachometer%20Conversion-R1.pdf
 
could I take the "guts" of a later Tac and drop it in to the 67 housing and face plate the whole in the 67 dash is very big.
 
I've heard of people doing that. You might also be able to get a later Spitfire tach and change the faceplate and/or bezel. The late Spitfire tachs are the same size as your '67, and were used by BL in the late 1500 Midget in the UK.
 
The late Spitfire tachs would be a good choice. They are RVC type and should be readily available.
 
Hmm, sorry to hijack, I hope you have all of your answers already.

I loved the linked article. My tach (posted this a few days ago) is on the fritz and putting a new one behind the face is exactly what I want to do. I have a 68 Sprite MK IV. Do I have to change to a pertronix ignition to get the proper signal and change to a more modern tach? What tachs would work in this configuration?

Ben
 
ok Ive pulled out the pertronix ignition
Ill deal with that later
so at the coil I have a white wire the Whitew/black trace and the wire that comes out of the destribuster
what do I stick where?
my 72 is happy with its Ignighter so its no help as refrence.
 
This is an answer i got from John Twist at University Motors. This may help a little.
Paul!

The earlier style tachometer senses the pulse on the power side of the coil. The later tachometers use a pulse from the distributor side of the coil.

The tach must have power -- from a GREEN, fused wire to the spade. It must be earthed (BLACK wire under one of the legs holding it against the dash).

The impulse loop must be connected from the key switch to the + post on the ignition coil (the - side of the coil goes to the distributor). The impulse loop will not drive the tach if the current is going in the wrong direction -- so hook it up one way first and if that doesn't work, reverse the position of the wires.

The reason your engine quit is because you applied power to the distributor side of the coil.

Hope this helps

John

Safety Fast!
John H Twist
University Motors Ltd
6490 Fulton Street East
Ada, Michigan 49301
616 682 0800
616 682 0801 fax
www.universitymotorsltd.com
 
This may also help:
Tachometer Conversion, Positive to Negative Ground

Items needed: soldering iron & solder, electic tape or heat shrink tube

Remove the tachometer from the dash, take it to a clean work site, on the seat of the car is not the place to work on the inside of your tach.
Remove the chrome bezel, glass lens,and inner black rim.
Remove the 2 screws from the back of the tach, these hold the mechanism to the housing.
Holding the tach by its face with the ignition light at 3 o'clock ( red line straight up ) locate the resistor which is soldered to the spade terminal that comes out the back. Locate the post imediatly to the resistors left, these must be reversed. Unsolder the resistor from the spade terminal, unsolder the green wire from the left post, solder the green wire to the spade terminal, solder the resistor to the left post.
Reassemble the tach into its housing replace rim, clean the lens, re-fit lens and chrome bezel.
Back in the car, you will have a white wire that makes a loop out of the harness and around a plastic terminal on the back of the tach, this loop must be reversed. Mark the wire 2 inches from each side of the loop, cut each side and switch the wire (reverse the loop) solder the connections and tape or shrink tube the bare wire.
Mark the tach on the outside of the housing NEGATIVE GROUND.
Install the tach in the dash, hook up the loop and green wire and be sure the housing is properly grounded.
If you do NOT agree with these ideas, if you are "mechanically challenged" or are just down right "stupid" I suggest you perchase New parts from a supplier of your choice and have a local shop do this work for you.

Frank Clarici

Electric Tachometer Face Swap for Bugeye

BUGEYE TACHOMETER CONVERSION

Many Bugeye owners are confronted with the problem of sorting out a tach drive once they have converted either to an alternator or discover that they cannot find a mechanical tach drive at a reasonable price. Frank Clarici offers a great piece of advice on how to convert an electronic tack over to negative ground. I have taken his advice one step further. Many Bugeye owners do not want to give up the stock look of the original gauges, so I have outlined here how to solve the tach drive as well as the stock looking gauges problem.

You will need:

original Bugeye tach
tach from a Mk3 Sprite or Mk2 Midget (this is an electric tach, the same diameter as the Bugeye)
Frank Clarici instructions on how to convert to negative ground (if your car is negative ground)
Small standard screwdriver
touch up paint (optional)
1 Hour labor Procedure:

Remove the front chrome ring, glass and seals from both tachometers by twisting the ring. The rubber seal on them may need to be replaced.
Very carefully remove the RPM indicator needle from each of the tachs by pulling straight off the post.
Using a small screwdriver remove the 2 small screws that hold the face plate of each tach.
The screw spacing is different for the faceplates, lay the Mk3 faceplate over the Bugeye face plate and using a small drill bit, drill the 2 holes in the proper location. Be very careful how much pressure you put on the faceplates as they are very soft and can be deformed.
(OPTIONAL) Use super glue to affix a thin patch to the backside of the faceplate or fill the hole with epoxy, to cosmetically close and paint the old screw holes in the Bugeye faceplate.
Install the Bugeye faceplate and RPM needle onto the electronic tachometer.
Reinstall the tach chrome ring and glass with new rubber seal if needed.
Install reconfigured tach into car dash and do electrical hook up. You will connect a 12 volt line to the spade connector on the rear, the case is grounded and a length of wire will go from the coil, loop around the sensor pickup on the rear of the tach, and back to the points terminal on the distributor.
It is that easy, drop me a line if you need more information,
Bob Magnotti
bob@itgonline.com
 
Someone with the rights needs to put this in the knowledge base. It has been an item of intrest here many times over the past months.

ahhh, square o rings are availavle, google em on the internet. These would be for the gages of course.
 
This is just to paraphrase what PaulSherman wrote above.

The RVI tachs (induction loop on the back) are current sensing and power to the coil passes through them. A white wire from the ignition switch goes to the loop on the back of the tach. The other wire leaving the loop goes to the high side of the coil (the side NOT connected to the distributor). As mentioned, you need a switched 12V supply for the power and a good earth connection. The white wire with the black trace (in the wiring harness) goes between the low side of the coil and the distributor. Also as mentioned, the direction of the current through the loop is important so if it doesn't work at first, switch the white wire connections.
 
thanks I got it to back fire a few times so Im finaly getting spark I think its onto timing and carbs.

what I have is the white from the igintion going though the loop and then to the high side of the coil. then a white wire from the harness going to the low side and the black and white to the distributer to the low side.
thanks every body
 
Im out in lexington
where are you? once I get on the road we could meet at an ice cream stand some where
 
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