Timing light troubles.

Fitted the Crane HI 6 ignition to No.8 Beetle. Starts and runs nicely, however when I tried to check the timing, there seems to be a problem.

With the timing light pointed at the pulley, in the usual way, and at around 3000 RPM, the timing 'dances' between about 20 and 40 degrees before TDC. It was set at 27, and I did not move the distributor. Maybe it's the 'multi-spark' ?

How do I correctly set the timing now? HELP!

Reply from MSD on the same topic; "There is nothing special that has to be done when setting the timing. The timing light will not pick up the multi-spark, the timing light can not pick them up due to the time frame at which it is occurring...." " ...do not use an adjustable or dial back timing light when setting the timing. These lights are very susceptible to noise and can give you an inaccurate timing reading when using an aftermarket ignition. Make sure that you are using a standard timing light with no adjustment and clip the pick up for the light up near the plug and not at the cap. This will provide you with the most accurate reading. There is no need to by pass the box when setting the timing." - http://www.thirdgen.org/techboard/tech-general-engine/73227-setting-ignition-timing-msd.html