My 312 has a Mallory Dual Point Dizzy with the Mallory coil.  I just bought a new Bosch Tachometer looks like the Sun Pro of the seventies.  Hooked it up to the negative terminal of the Mallory Coil
Seems like the RPMs are reading double.  I am thinking I should switch the tacho's setting to 4 cylinder.
Any thoughts on this.
Thanks,
Richardii