Crank Trigger Crossover Switch Failures

What about a larger diameter trigger wheel?....

 

I'd consider the FIE setup as the components are encased in epoxy. When I used it, it worked great. That is until I broke a belt and the belt cleaned off the wires, lol. I start mine on 12v with a cheapo starter and it works fine until you get the phase off when using the crank trigger.

 

Wouldn't the periphery speed be higher for a bigger diameter wheel at the same RPM?.....

 

Okay, I'm still not getting it. Maybe you can clue me in offline?....

 

This thread is proof of why we have the lame trigger setups on our cars.
Apply bandaids until the engine will make noise.

I could never get an answer for why the magneto trigger is so powerful.
They are both an a/c generator.
There is a noticable amplitude difference between trigger types and gaps.
The closer gap increases the amplitude and low speed generation for starting but carries a noise penalty.
I can tell you that the Lahey trigger makes the most voltage but we seemed to get the cleanest signal with the MSD type with stainless jacket.

 

There has to be something else affecting the signal. The crank magnet moves past the sensor at a much higher speed than the mag. First of all the crank wheel is spinning at twice the speed of the mag in RPM alone. The surface speed of a 7 inch wheel is approximately 146 inches per second at 200 RPM cranking speed. A 3 inch (estimated) mag pickup surface speed is less than 16 inches per second at 100 RPM (1/2 crank speed) The crank magnet is therefore spinning over 9 times faster past the sensor. Please correct me if I am wrong.

 

DMy math was wrong on the crank magnet speed. I accidentally doubled it. Even correcting for that it is still a much faster magnet speed. As for the mag, it has 8 versus 4 in the crank. I could be wrong on this but I believe the mag has a larger fixed magnet and the reluctor wheel passes through the magnetic field whereas the crank has the magnet pass through a non-magnetic pickup. The mag pickup is a stronger signal but less accurate in relation to the crank/pistons due to gear slop, etc. The crank trigger is weaker at slow speed, but more accurate in relation to the position of the piston. None of this solves Mike's crossover switch problem, but I'm trying to fully understand the reason he needs/wants the switch

 

You could try here ..... http://www.itwswitches.com/Mil_Aero.shtml#

 

Just a thought Mike, but would it not work to have both triggers plugged in, in parallel to start the engine and then simply unplug the mag head plug while it is running? The signals should be very close and if a second one collapsed the field a second time a nano later, so what, the rotor position is still pointed at the same plug lead.
So no switch at all, just parallel leads. Jeff J.

 

Of course you know your mag setup and phasing but if it would be off enough to be a problem, the mag could be put in any position for starting only, correctly phased and the crank trigger placed for running only, correctly phased for your advance/retard swing. Even if it would get a double signal to the coil, the ignition would only collapse twice and think it was running at twice the speed and the rotor can only deliver spark to the post it is aimed at. And so what if it even gave the plug a double spark while it is sitting there idling? It would only be a spark into an already lit cylinder. The Nitro cars used to run both mags a bit out of phase and do exactly this and under power I believe.
Jeff Johnsen

 

You guys all know way more about this than me. But I don't get why you guys just don't run a blower starter, it would save you weight, and as yuo guys run outlaw stuff there is no need for the onboard starter. I never had a no start on my 48 volt blower starter. i don't even have a crossover switch. so less stuff to fail and maintain.

 

Ahh ok my mistake. i thought you guys only ran outlaw stuff.