....THANKS Hank, Chris & Denny, Yes I think I started that thread r/e 'What Timing Light Should I Buy'? & you all told me that some timing lights don't work with an MSD Box. So I bought the MSD #8990. I will get the tape as I just talked to the guy who built the motor & he said to set the timing at 35 degrees advance at 3000 RPM. And that the idle timing is just 'whatever' it happens to be..... But I'm confused on the functions of my Retard Knob. Two more questions please; 1) Wouldn't the tape that I get depend on the diameter of the harmonic balancer that I have??? & 2) I'm confused on the Retard Knob. The guy said he set the timing with the knob at 9 & to just move the knob up or down depending on whether I wanted to advance or retard the timing. But you said the knob will ONLY RETARD the timing???? THANKS Bill