[scottj]

I always used a Snap-On dial-back and it seemed to work fine. Then my engine builder said to never use it on the new motor. Being skeptical, I called and spoke to an MSD tech. He told me that a fluctuating reading is not the only problem, it is possible to have a perfectly steady, but inaccurate reading with the dial-back lights due to the RF that the MSD emits.

For most applications, the risk involved from using a dial-back light is not that great, but on an engine that will be destroyed by running a few degrees advanced it's just plane foolish to use a dial-back light.

Scott