[Andy67mustang123]

Hi i have just purchased the gauges that has factory tacho
but my car just had the factory non tach wiring i would like to hook it all up but unsure how
the previouse owner has installed a idiot light under the dash so i assume i could just take those wires and make that light be my alt light in the tach?
But I am unsure how the oil light part goes
And i am also running msd gal ignition and dizzy, do i need a msd tach adapter to make that work
Newbee here
Any help would be great thanks

 

[caveeagle]

You need different sending unit/switches for the amp/oil pressure indicator lights. I looked over my wiring diagram but cannot see any notes that show a tach signal wire.

can you post a picture of the back of your tach cluster? I would also like to know where the tach signal ties into the under-dash harness

 

[GT289]

Can't speak to your exact wiring situation but the factory tach is referred to as Current Sensing. If you have an MSD box, it'll have a terminal for a tach that will work
along with an MSD 8920 tach adapter to power your factory tach.
See post #2 in this thread for the basic concept.

Msd tach adapter

I havr a msd 6a box, is the msd 8910 the correct adapter to use with the factory tachometer? Thanks

www.vintage-mustang.com

 

[TheRktmn]

This is how to wire a factory tach. To use with an MSD ignition box you will need an adapter or the tach has to be converted to read the MSD signal.

 

[Andy67mustang123]

On the back of this it says the grey wire is the tacho wire, so do i use that with a msd 8920 tach adapter?
Also how do i do the amp light?
The oil sending unit i have read i need to get a diffrent one to make that light work
Still trying to research what one and how to wire that also
This is my current set up what im running

 

[Hemikiller]

Yes, sorta - see the current triggered tach setup below for the 8920.

https://documents.holley.com/8920.pdf

 

[Andy67mustang123]

Ok thanks for ya help guys
So since i will be running a 67 factory tach and have msd 6al & msd blaster 2 coil..
as mentioned above they are current sensing tach i just need to buy a msd 8920 & wire it as this picture
Great i understand that part now any advice on how to make the idiot light work thru the tach gauge where its ment to be?
The previouse owner has installed one in the engine bay so was thinking of tracing the wires back and linking it up to the spot in the gauge?
Also any advice on the oil gauge?
Thanks in advance

 

[CJM68GT390]

I can only speak to the '68. Because the tach cluster has an idiot light for the alternator, while the non-tach cluster has an amp meter, the under-dash and headlight harnesses are both different. I have never been able to find an actual wiring diagram/schematic for my tach cluster car. I do know that there is a 15 ohm resister in parallel to the idiot light (so if the light burns out there is still a circuit) but I haven't located it yet, but I'm working on it.

 

[caveeagle]

thats why I asked you to post a pic of the back of your tach cluster. I am guessing that the amp and oil lights wire back to the same pins on your cluster harness and the corresponding pins on the underdash harness.

if this is true, all you need to do is change out the sending units. The “non tach” cars have senders that modulate ground resistance in a range that makes your gauge needles move.

there should be different sending units that are more of an Off/On based on a pre determined setpoint. The wire that goes from your cluster to the sensor doesn’t really care.

we can confirm my “theory” by tracing the wires on your tach cluster back to the harness plug / pin location.

 

[Andy67mustang123]

Ok i think i mite need to track down a wiring diagram for the dash as im hoping to hook it up to a non tach dash loom

 

[vtgearhead]

I'm going to make a recommendation. This is only valid if you're not concerned about strict originality.
1 - send the tach to Rocketman for electronic conversion. Then, wiring is easier (uses more standard tach wire). The MSD box may have a tach line, no adapter required. It is also much more accurate.
2 - buy a 68 oil pressure gauge and mount it where the clock (or blank) section is. That will use the same wiring you have now.

I like the result much better.

 

[caveeagle]

It looks like Rocketman is offline for "re-tooling" for a while.. (from the site)..

I do like the idea of using the '67 oil pressure gauge, and that is the route I am going with my build. I am working with someone to 3d print a bracket to mount the 68 gauge in the "clock" hole. I will post up pics when that working to my satisfaction...

I do not have an OEM tach to work with, so I am working out my own solution using a Speedhut 4.5" gauge.

Andy, do you have the cluster wiring? if not, I suggest you might want to source a repo or used cluster hardness. Are you working with a stock under-dash harness? Depending on what you are working with, my recomendations will probably change..

 

[CJM68GT390]

One further point, regarding the '68 dash, the non-tach cluster has 2 connectors of 8 pins each (not including the wiper switch) while the tach cluster has an 8 pin connector, a 6 pin connector and two single connectors for the tack itself.
If anyone has a tach cluster electrical schematic I'd love to see it.

 

[caveeagle]

One further point, regarding the '68 dash, the non-tach cluster has 2 connectors of 8 pins each (not including the wiper switch) while the tach cluster has an 8 pin connector, a 6 pin connector and two single connectors for the tack itself.
If anyone has a tach cluster electrical schematic I'd love to see it.

my 67 standard cluster has two connectors (+wiper switch). A 12-pin plug and a 2-pin plug.

if I didn’t care about originality, I might get one of the painless connectors to tie it all together into one plug.

currenty, I have added a 3-wire plug to account for the added tachometer

 

[Andy67mustang123]

Hi thanks for your input guys
Big learning curve for me..
pic above is the gauges im waiting to arrive in the post & this is my current set of gauges, i will be pulling them out on the weekend to see what it looks like behind them
And yes i would like to keep the original look, mate has suggested to put a oil gauge in the clock space rather than relay on a oil light

 

[caveeagle]

I am right In the middle of adding the 68 oil pressure gauge to the middle of my 67 Cluster. if you are starting with 68 cluster, then I think you have to source a 67 fuel gauge and move things around to free up the large tach spot.
here are some pics of what I have in progress...

 

[Andy67mustang123]

Oh sorry for the confussion guys car is 67 with a 68 dash surround.. it came with the car and was a bit tidyer than the current one that was in it

 

[Andy67mustang123]

Hi i finally got my gauges sent away to get checked over and fixed
Now i have them back good to go in the car
They said the workings of my tacho was stuffed so put a new guts in the back he has labled it red = +ve black = -ve yellow = pulse
But im unsure which wires to switch round back there as now the ampmeter & oil pressure gauge that was installed is ditched an also now has its own gas gauge in different location
I see there is a video on youtube autorestomod but his tach mite be set up different?
Its the finishing touch to driving my car but i want to make sure the wires are right before i plug it in

 

[Magnus]

Since nobody else is jumping in here with crazy wiring suggestions I'll start.

Looking at the wiring diagrams I think the red wire formerly used for the Amp gauge should be a good 12v+ source. Double check it, but that should probably work for your Red VE+ line.

The best ground for the Black VE- is probably the bolt that holds the voltage regulator on. It's right next to the speedo cable.

The Yellow Pulse wire is going to have to go to the ignition coil on the engine. Since you didn't have a tach before there's not going to be a wire for that, you're going to run that one yourself.

If you want the low oil pressure light to work you're going to have to get a light bulb obviously but you'll also need to change the sending unit on the engine to the 'warning light' model. It's basically an on-off switch. If you did that I think you could probably just hook the original oil pressure gauge wires up to your light bulb and it'd probably just work.

I have no idea how you'd make the ALT warning light work. Hopefully somebody will jump in here to say everything I've typed is wrong and they'll know how to fix that light too.

 

[Andy67mustang123]

Since nobody else is jumping in here with crazy wiring suggestions I'll start.

Looking at the wiring diagrams I think the red wire formerly used for the Amp gauge should be a good 12v+ source. Double check it, but that should probably work for your Red VE+ line.

The best ground for the Black VE- is probably the bolt that holds the voltage regulator on. It's right next to the speedo cable.

The Yellow Pulse wire is going to have to go to the ignition coil on the engine. Since you didn't have a tach before there's not going to be a wire for that, you're going to run that one yourself.

If you want the low oil pressure light to work you're going to have to get a light bulb obviously but you'll also need to change the sending unit on the engine to the 'warning light' model. It's basically an on-off switch. If you did that I think you could probably just hook the original oil pressure gauge wires up to your light bulb and it'd probably just work.

I have no idea how you'd make the ALT warning light work. Hopefully somebody will jump in here to say everything I've typed is wrong and they'll know how to fix that light too.

Hi thanks for your reply
I am still stuck on the first step before i hook up the tacho, i have installed a clock in the middle an that works so does my gas gauge
I have dash lights that work an dim but when i put my hi beam lights on i do not have a light working.. have checked all bulbs are good

i have removed the red and yellow wire that was for my ammeter an taped them off
Also taped off the white with red strip and a black wire which was my oil pressure gauge

Now when i turn my intercators on left or right they blink really fast on the dash and also at the front an rear
But when i put the hazard lights on they blink at normal speed on dash and on front an rear

Any idea whats going on?
I have read somewhere on this fourm to make a alt light work that i need to switch S to I on my regulator and also run a new wire from S to the S post on the alternator..
I am yet to do that change along with the other steps for the alternator light

I have brought the correct fitting for the motor for my oil light

Before i plug in the tacho or go any further with alt oil light i would like to get the above issue sorted before i move onto the next challange