I have a 1980 ford f 150 4x4 and i changed the ignition over to msd. Wonder how to hook it up so the factory tach will work?

 

If you look in your instructions on page 7, they tell you if the special tach terminal on the msd unit will not operate your tach correctly, then you need to get a tach adapter #8910 or #8920, depending on how you hooked the box up.

 

okay well atm im not really sure what to hook to to get the factory tach to work.

 

I don't have my diagrams with me, but I think it should have been a wire that hooked to the negative of the coil in the old system. It may have branched off at the old ford ignition box. Have any wires left over hanging after the new install?

 

don't know if this helps but i installed msd box and distrubor and coil and my stock tach works great

 

I have a 1980 F350 400 with a Crane ignition - distributor, module and coil - and I suspect that the tach wiring for the MSD is probably the same. The green wire that used to connect to the coil neg should be connected to the MSD tach feed wire. Then locate the black with green dot wire that used to go from the Duraspark module to the duraspark distributor ground and make sure that wire is grounded to the frame or wherever you choose. The combination of the MSD tach feed to the green tach wire and the black with green dot wire to ground completes the tach circuit.