Question on MSD pro mag crossover switch

I've heard several people say that you can't start the car on the crank trigger, you need the switch to start it on the mag. Why is this?

Hey, Just realized I made ITA pro.....gotta go celebrate!

Thanks,
Trevor Sherwood
727-364-4368

 

You absolutely can start them on the crank trigger. The mag must be phased right and you need adequate cranking speed.

 

change over switch.

It really has to do with cranking speed. It takes less RPM's off the Mag. I run a 6 shooter with leahey stuff. I change it over when getting ready to stage, so the timers are not on until then.first the boxes and then the trigger. If something happens, I can switch back to the Mag real quick . You can catch it real fast. I like it that way. Don

 

leathy crank trigger

I dont have a crossover switch
We start the car with rcd starter with 36 volts, 3 full size car batteries (CCA)
when we switched from roots to the screw i was concerned we might have to add the switch but it never has been a problem

 

One thing to remember, when switching from a roots to a screw, the screw has so much more overdrive, when using a blower mount starter, the motor will spin slower because of the small blower pulley. We had a random problem of the motor not starting. I ran the data logger during the startup and saw the motor was`nt spinning over the required 250 RPM for a mag 44. Went to 48 volts and never had the problem again. Tom.

 

we use on board stock starter, 24 volt cranking

I use a 24 volt relay wired to the starter so while cranking relay switches to mag trigger and when you let off starter button relay turns off and switches to Leahy trigger