MSD Ignition and weird run-on

[Jim_Newman]

The new MSD ignition system recently installed works great. I find no significant difference in overall performance but the tendency for pinging at low-RPM, full-throttle has finally gone away. (She has triple Webers, high compression pistons, etc.)
HOWEVER, when the ignition is turned OFF, even by the cut-off switch (which is in the cockpit), the car keeps running for 2 or 3 seconds before stopping!! Other ignition related functions, like the horn also function during that time. What is that all about??
As always, any thoughts are appreciated.
Cheers

 

[HealeyRick]

Try contacting MSD. They have a forum here: https://www.msdignition.com/forum/forumdisplay.php?f=8&order=desc and you can call them on their tech support line which is listed on the forum

 

[57_BN4]

Can happen if an electric fan is running when the engine is turned off

 

[red57]

Sounds to me like you have an alternator instead of the generator and the alternator is still putting out juice after the key is off. I'm no electrician and don't know how to correct it but I installed a 240Z alternator in mine a long time ago. It seems like it takes a second or two to quit charging & then it stops. I has always done that since I made that change, I just stop it with the clutch (like you would do for any 'run-on' situation).

Seems like a possibility anyway

 

[Jim_Newman]

You may be right RED57, I do have an alternator but this did not happen before I installed the MSD. Maybe that big capacitor retains enough juice to keep things going for a while - even though the battery is out of the picture.