Mag vs. P-mag pulse per revolution

I am preparing to replace my non-impulse coupled Slick mag with a P-mag.

The Slick mag has the electronic tach pickup for my VM1000 in it.

Emagair sez their P-mag sends out two pulses per engine revolution for their electronic tach signal.

Does anyone know if a Slick mag also puts out two pulses per rev, or am I going to have to change the pulse count multiplier in the VM1000? This would not be difficult, just inconvienient.

I get conflicting info from Emagair and Microvision, so I might have to use trial and error to get the answer, but I thought I would try this forum first.

Thanks,
Ben Beaird
-6A

Mags put out 2 pulses per revolution. This is called a 'wasted spark' system. The plugs fire every revolution, even during the exhaust stroke.

This means that you don't have to time the mags knowing when the exhaust or intake stroke is, just the position of the crankshaft.

Vern Little
9A

Vern,

I'm not sure you're correct here. Mags will put out 2 pulses per rev down the P-lead as they have to fire 4 times every 2 revs. They have a distributor so don't use the wasted spark system.

E-mag have a separate tach lead and generate a 5v (I think) pulse down the lead twice a rev. I don't think its anything to do with the wasted spark system as the pulse comes from the electronics, not from the coil.

If its anything like a GRT EIS the only change that may be required for the tach signal when switching over from a mag to a P-mag is taking out the resistor from the P-lead to the VM1000. The resistor is to ensure a short in the engine monitor does not ground out the mag and switch it off - with the P-mag its not an issue as the P-lead and tach functions are on different wires.

Pete

Pete, you're right. I must be thinking of my weedeater. Nevertheless the P-lead coupling generates two pulses per revolution, that's what I've programmed into my EMON.