Let me start by saying I have searched the forum for all the information I
could find about 1980-86 factory tach info. I this week got a NOS factory
tach off of E-bay. It was listed as an PN E0TZ-17360-A. When I received it the Ford box PN was E4FZ-17360-A. The number on the tach
itself is E4EF-17360-F. The tach looks like it will fit. Another difference
is that the tach has a white needle and a colored Yellow/red RPM limit on
it. Looking at the pictures in a 1981 brochure it shows a tach that has
no RPM limit colors. The most important question I have is about the
hookup. This tach has only 3 terminals on the back, B, C and G. The ones I have seen in pictures on the forum and the other info indicates 4
terminals on the back.

My questions are:

1- What tach do I actually have and will it fit the cluster?

2- My truck is a 1981 F100 with a 351W and an MSD ignition. I have a
aftermarket VDO tach hooked up anit works well. My truck has factory
gauges and I know about the circuit board differences and I think the
best way to install this tach is to hardwire it.

3- What are more experienced members thoughs on will this tach work
OK if I hook the tach signal to the C terminal, a keyed 12V to the
B terminal and ground the G terminal. That is basically how my
aftermarket tach is now hooked up.

Any info and opinions would be appreciated. I can return this tach if
it won't work for my application.

 

Number Dummy can help with the part numbers, but as long as it's a 6K rpm or greater tach, it will work wired that way. If you have a gauge set in the truck, I would recommend you use the existing wires as follows.

Splice the wire from "B" to the black/green resistor wire at pin 1. This is a resistor wire. If you peel back the wrap on the cluster harness, you'll find a pigtail to splice to. This factory setup the uses the resistor.

Splice the wire from "G" to black wire at pin 2 ground.

Spilce the wire from "C" to dark green/yellow wire at pin 11 tach input.

 

Where does the yellow and red start? (RPM-wise)
This sounds like it may be the elusive diesel tach.....

 

Wow....I didn't even pick up on that...hmmm....sounds like time for a new experiment...

 

From what I can see the only difference is that on a diesel truck the dark green/yellow wire goes to an engine speed sensor instead of a coil. It'll wire the same way. The only question is whether the diesel tach operates on the same input frequency as the gas tach. I'm thinking that it will.

 

The third digit in the part number suggests it belongs to a car.

 

The RPM scale goes to 7000. The yellow starts at 5500 and goes to 6000 and red runs
from 6000 to 7000. As 81-F-150-Explorer mentioned, it looks like this thing is not what
it's susposed to be. It's also about 4 inches in diameter. I am still also concerned about
the terminals on the back, this tach has only 3 instead of 4 like the pictures of truck tachs have. If I determine what this is for sure I may have to return it.

 

Can you post a picture of it? If it's round it doesn't goes in one of our trucks.

 

I can't post a picture of it. It now seems to me that this is a car tach due to the 7000
RPM scale. I will do some more searching to find out what it really goes on but it seems
like I will be returning it to the seller unless I can find out different.

 

One of your earlier posts seemed to indicate it was round. The truck tachs were rectangular. If it's round, it's definitely the wrong tach for the F-Series. it doesn't really matter what it goes in.

 

I think you're right Bill. It's round and squared off at the bottom. But like you said this
tach is not for an F series so I think it will be going back. Thanks to all that helped
ID this tach.