[71Chev]

The following instructions are from (user) Original69.

Z28 Tach in a 67-72 truck.

Parts needed are the tach, at least 8ft wire. Crimp on ends, 6 nuts same size as the z28
guage studs, grommet, plastic cleaner, drill bit etc. I’m sure I missed something..


Here is an overveiw of the tach install. I used a tach from a 79 Z28 cluster.

1-Dissasemble the rear cover by removing the screws on the edge. I think
there are 8 of them . Set it aside.
2-Take out the black metal plate and set it aside.
3-Take the plastic plate out and you will need to remove the lines in white
that are there. I used a Meguires plastic cleaner and a whole lot of rubbing.
Be careful not to remove any of the other white lines, only the ones where
The tach is going.
4-Get the metal plate, the one with the black side and you will need to
remove the area where the tach will be. I removed just the circle area to
the edge. The tach circumference should be about ½' larger than the circle you are cutting out.
Go slow here and do a good job
5-You will have to trim off the small tab on the tach where it sticks out.
Don’t worry about the small notch that’s there, you won’t see it when
It’s done. I did cut two small pieces off of the edge for the dash lites to
Show thru at night. About ¼'
6-Put the tach where it goes. I had the bend the bottom and top edges with
small pliers before it would fit.
7-Take the tach back out and you will have to do some work to it now.
8-The tach has 3 studs coming thru an insulator plate. This will have to be
removed. I took the 3 nuts and insulator off marking on paper where
wires went. (grnd, pos, tach). You will have to screw the 2 small nuts
on the studs one at a time to DOUBLE NUT them before you cut them.
I used a cutoff wheel and cut close to the top nut. Then back one nut off
and when you do all three hook the three new wires onto the shortened studs.
9-Put the tach back into the cluster and turn it around finding the
best fit in the front. I used sheet metal screws to hold it in. You
can drill a small hole then screw the sheet metal screws in close
along side the tach. This will not show in the front and is good enough
to hold the tach from moving.
10-Now take the rear metal piece and figure out where the tach screws
could possibly hit. It is very close here. If you need room take the
plastic circuit piece off, then use a small ball peen hammer and
hit it a few times to bulge it out some. Be careful you don’t hit
it out too far as the circuit plastic might not want to go back on.
Mine is very tight but I needed the clearance inside.
11-Drill a small hole big enough for the 3 wires and a rubber grommet
to pass thru the rear plate.
12-Check everything before you screw it all back together to make sure.
I also put a few pieces of electrical tape where the studs might hit the
inside of the rear plate.