Recently acquired a 1969 Mercury 65 HP outboard and would like to add
a tachometer. It's the 650 model with Thunderbolt ignition and a
label under the cowl warns me about using any tachs not designed for
the motor. The control box up front does have a 3-prong receptacle
for a tach, but I haven't had much luck finding one to fit.

Do I really risk hurting the motor by using a non-Merc tach? Could I
just go inside the control box and hook up a modern aftermarket tach?

Thanks in advance.

Dave

Take a look at the teleflex site. They have some good guage info

http://www.tflx.com/obtachsel.html

(Dave Bohnsack) wrote in message om...
Recently acquired a 1969 Mercury 65 HP outboard and would like to add
a tachometer. It's the 650 model with Thunderbolt ignition and a
label under the cowl warns me about using any tachs not designed for
the motor. The control box up front does have a 3-prong receptacle
for a tach, but I haven't had much luck finding one to fit.

Do I really risk hurting the motor by using a non-Merc tach? Could I
just go inside the control box and hook up a modern aftermarket tach?

Thanks in advance.

Dave


It might depend on whether the original Merc tach was designed to use
pulses from the alternator stator or from the ignition system. The
aftermarket tach probably uses stator pulses. You need someone with
the wiring diagram for your motor to give you the straight skinny.

%mod%