Tachometer hook up

I have installed an MSD ready to run distributor along with an MSD coil.  I need to connect the gray wire from the distributor to the tachometer input of the car. Could someone direct me as to how and where to connect the gray wire from the distributor?  The instructions don't indicate having to add an additional tachometer adapter.

The tachometer is a stock unit.

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I have installed an MSD ready to run distributor along with an MSD coil.  I need to connect the gray wire from the distributor to the tachometer input of the car. Could someone direct me as to how and where to connect the gray wire from the distributor?  The instructions don't indicate having to add an additional tachometer adapter.

The tachometer is a stock unit.

Click to expand...

If you have a factory tach, it is not "ready to run".  You must use the MSD tach adapter.  

If you have an aftermarket tach, simply attach the gray line to the signal line going to the tach.

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I have installed an MSD ready to run distributor along with an MSD coil.  I need to connect the gray wire from the distributor to the tachometer input of the car. Could someone direct me as to how and where to connect the gray wire from the distributor?  The instructions don't indicate having to add an additional tachometer adapter.

The tachometer is a stock unit.

Click to expand...

If you have a factory tach, it is not "ready to run".  You must use the MSD tach adapter.  

If you have an aftermarket tach, simply attach the gray line to the signal line going to the tach.

Click to expand...

Midlife,

thank you for your response.  I did some research after reading your response. In order to install the MSD tach adapter, I also need to install an ignition control module MSD 6AL. I have attached a wiring diagram illustrating the ignition module and tach adapter wiring. I have also used the Mustang ignition, charging, and starting with tachometer wiring diagram to try and understand how this works. I have a few questions before ordering.

Looking at the diagram, from the key location It shows to splice points. I believe this wire is #16, red with light green stripe. One splice is going to the tachometer. I believe this spice is made somewhere in the harness or under dash.

The next splice is shown going to the tach adapter and msd ignition control. This would be a splice that I would make onto wire #16 red with light green stripe.

I understand the rest of the wiring in the diagram with the exception of the connection of the violet wire from the tach adapter, to the trigger wire of the tach. I don't know where to locate that trigger wire.

Looking at the diagram in my first posting, it shows the gray wire from the distributor going to the tach trigger wire. In the second diagram I have posted it shows a violet wire going to the tach trigger wire. Is the tach adapter only needed when using the ignition control module?

It appears to me I'm adding to new components, the tach adapter and ignition control module, but still needing to find the tach trigger wire.

Thanks

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Your factory tach does not read the signal that the MSD R2R puts out. The MSD hook-up (grey wire) is a square  wave voltage signal created by the coil field collapsing and is picked up from the coil - post. The grey wire is a synthetic signal that emulates the square wave.  Your factory tach is current sensing and reads the amount of current going into the coil on the + post.  Basically you are asking an 1157 tail light bulb to illuminate in your kitchen ceiling light socket.

Unless the R2R is something other than the MSD version of a GM HEI (all in one electronic ignition) the factory tach 'should*' work normally with a factory hook up. Ignore the grey wire, keep the factory ignition circuit intact. Any change to the factory circuit will effect the tach and it's accuracy as well as it's lifespan.

*'should' because Faria tachometers are notorious for failing. I am pretty sure that Faria considers any tach that works beyond the three year 36,000 mile Ford warranty a design failure.

Factory hook-up:  Ignition ON --> tach Red wire...through tach to tach Black wire --> 'pink' resistor wire --> coil + post.



This is a simplified drawing but still applies to all Ford current sensing (series) tachs:

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Rktmn,

Thank you. I will leave it hooked up without the gray MSD wire. I have new motor installed and want to know my rpm range when I start the motor for the first time.

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Rktmn,

Thank you. I will leave it hooked up without the gray MSD wire. I have new motor installed and want to know my rpm range when I start the motor for the first time.

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For the sake of accuracy when breaking in the cam and setting timing I would purchase an aftermarket tach and hook up under the hood so you can watch rpm range during start up, break-in, and tuning.

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I have a timing light with a tach readout and a remote starter switch. They really come in handy while staring engine for first time, especially if you’re doing it by yourself.

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Rktmn,

Thank you. I will leave it hooked up without the gray MSD wire. I have new motor installed and want to know my rpm range when I start the motor for the first time.

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