Forum for discussion of MG and MGB motorsports, historic and current (SCCA, NASA, VARA, etc) car preparation, engine, bodywork, suspension, drivetrain modification.
I need to calibrate a tachometer I bought from Auto Meter nearly two years ago. It has the different color wires that you cut depending on whether you have an 8, 6 or 4 cylinder to ensure that it is in sync.
The wires I cut are based on the Pulse Per Revolution (PPR). So, does the MGB with a Mallory Unilite distributor have 1 pulse per revolution, or two?
Not four? Or do you mean one pulse per ignition event (yes) or one pulse per engine revolution (no, two)?
It gives one pulse per cycle. Some ignitions fire on both the intake and exhaust stroke (think crank triggered systems, aka wasted spark systems, where the crank makes 2 revolutions for every 1 revolution of the camshaft). Yours fires once.