65 Mustang: Tried to install a tachometer from Oreilly's with no success.

[spearce]

65 Mustang: Tried to install a tachometer from Oreilly's with no success.

1. I pulled out the dash cluster and attached the red wire to the prod or the threaded bolt attached to the back of the ignition and put a nut and tightened that on.
2. There was a screw back there that attached to the cars metal and already had another ground there so I attached the black wire there.
3. I left the white wire unattached for now and shouldn't effect anything since its the tachs back-light.
4. Last, I ran the green wire through the firewall and attached it to my MSD ignition coils negative side. From what everything I have read this should do it but it didnt.

 

[LILCBRA]

65 Mustang: Tried to install a tachometer from Oreilly's with no success.

1. I pulled out the dash cluster and attached the red wire to the prod or bolt attached to the back of the ignition and bolted that on.
2. There was a screw back there that attached to the cars metal and already had another ground there so I attached the black wire there.
3. I left the white wire unattached for now and shouldn't effect anything since its the tachs back-light.
4. Last, I ran the green wire through the firewall and attached it to my MSH ignition coils negative side. From what everything I have read this should do it but it didnt.

You hooked the red 12+ wire to the stud on the back of the ignition switch - am I understanding you correctly? I believe you'll want to splice it onto terminal B as indicated in this illustration.

 

[LILCBRA]

Another view, hopefully the wire colors are more helpful.

(Illustrations courtesy @mrglaeser and @dbo_texas over on thefactoryfiveforum.com)

 

[spearce]

Thank you, I will give it another go with your diagrams and descriptions.

 

[LILCBRA]

Oh, another thing - you said you have an MSD coil (sorry, your original post said it was something different and kinda threw me....) - are you running an MSD box like a 6AL? I'm assuming no since you followed the directions for a car that isn't equipped. If you do have an MSD of some sort, you'll need to connect the green wire to the tach output from the ignition box. Since the MSD has multiple sparks per cylinder per power stroke at certain RPMs, the tach will have issues reading it. The tach output from the MSD box is intended to correct that function. Here is a 6AL diagram.

 

[spearce]

Shoot, I think I need to start over as I am sending or writing down the wrong info here I believe. I do have a MSD 6AL 6201 box and I see the previous owners added a MSD tach adapter but nothing was wired up right(some wires not wired at all). Sounds like the way I was first trying to install the tach was wrong. If you think I dont need the tach adapter I would be more than happy to pull that out.

Here is what I think I am reading if I do need to use the adapter(MSD Tach Adapter 8920):
- MSD 6AL box grey wire needs to attach to the white wire on the tach adapter.
- Tach adapter purple wire needs to attach to the green wire from the tach
- Black wire from tach adapter need to be grounded to car metal near adapter.
- Red wire from tach adapter.... I am not 100% certain where this should go.

For tach itself, there are 4 wires(green, red, black and white):
- Red wire need to go to keyed ignition start hot, probably behind ignition maybe.
- Black wire ground to car metal/chassis
- Green wire mentioned above to purple wire coming from tach adapter
- White wire connects to dash lights switch I think.

Huge thanks for all your great information, I feel like I am close..... I think.

Let me know if you think the above sounds about right?

 

[LILCBRA]

Sorry I missed your post over the weekend. I don't believe you'll need the tach adapter for an aftermarket tach.

 

[LILCBRA]

Hopefully these links work, but these are instructions for both the MSD and the tach that is listed on O'Reilly's site for reference.

https://www.iequus.com/pub/media/manuals/93-0012.revE.pdf

https://www.mpsracing.com/instructions/msd/wiringmanual.pdf

The MSD manual looks like it covers all of their products. If you go to pages 8-9 of the MSD instructions, you'll find guidance for wiring a tach or tach adapter. Going further back, around page 146, you'll find a diagram for wiring the tach adapter. There are also instructions for wiring your 6AL. I included the directions for what I assume is your tach for reference. So, what I can gather from all of this - assuming your car runs and everything else is up to snuff and all you're looking to do is get this tach installed and working as it should - is to run the green wire from the tach to the grey wire of the MSD. If this doesn't work, then you'd install the tach adapter, wire as indicated, and try again.

 

[LILCBRA]

Just curious - have you gotten your tach working?

 

[spearce]

Unfortunately not. I took a break form this as it got frustrating. Moved onto replacing my pinion seals. No longer leaking from rear :- )

 

[spearce]

Just curious - have you gotten your tach working?

Unfortunately not. I took a break form this as it got frustrating. Moved onto replacing my pinion seals. No longer leaking from rear :- )

Just curious - have you gotten our tach working?

 

[LILCBRA]

No longer leaking from rear :- )

This is always a positive thing.

 

[spearce]

Unfortunately not. I took a break form this as it got frustrating. Moved onto replacing my pinion seals. No longer leaking from rear :- )

Sorry, meant to get back to this thread, I did end up getting the tach to work with the help from a local mechanic.