I'm going to redo my timing today. My 4.3 TBI has a mild comp cam in it, bored over .060, and a MSD ignition system. Anyhow, the speed shop who built my motor suggested 10 BTDC initial time, and 37 BTDC total time. I know how to set initial time, however, how do I do total? He instructed me, after setting the inital time, to rev the motor to 1500 RPM and adjust the distributor to 37 degrees BTDC. Does this mean just adding 27 more degrees, or 37 by the light/gun?
Also, comp recommends 6-8 BTDC on initial and no more than 34 on total. Trying to figure out why the builder suggested 10 initial and 37 total.... Here are the cam specs: 09-412-8 - Magnum
Note* When this was first done, I did what he said, and kept getting piston rattle on his recommended settings, so basically what I did, was to set initial time, and then adjusted the distributor slowly on a hill. I would goose it in 2nd gear up the hill, and bump it an 1/8" advanced, until it wanted to stall. At that point, I backed it off an 1/8, and solved the ping. been running it like this now for about 7 months. I run 93 octane. Nothing else.