MSD ignition
 

Just put new msd ignition and msd distributor on my car, and at idle the rpm jumps around about 300 rpm. Timing is set at 36 degrees and I have 1 blue spring and 1 light silver spring in distributor with a blue bushing. Any suggestions on getting it to idle without jumping up and down?

Re: MSD ignition
 

We run both light silver springs if we do not lock out the distributor.
Simple job to rotate distributor on shaft to lock it. If that fixes it it
is probably advance springs......Drag cars often work fine with it locked
even without starting retard.

Re: MSD ignition
 

I'd suggest that you verify with a timing light that a timing variation is the cause of your idle changing - if it is, just change to a bit stiffer spring.

Re: MSD ignition
 

Like John said lock it out and forget about it.

Re: MSD ignition
 

I've seen a bad plug wire make the timing jump around on a locked out distributor u mite check them