prestige6

I have a 454 with about 450 HP. I'm changing the Dist. To petronix and coil,with a MSD box. What should I gap the plugs at, and what should the timing be set at. No Vacum advance in Dist. Full Mechanical.

midyearvette

what's your compression ratio??

Ironcross

The best plug gap is .035 whether electronic or points...and the lead is 8-14 with premium gas 93/94 octane....

winning is not everything, its the only thing.....

Frankie the Fink

The Pertronix instructions will tell you that you can open the gap another .05 (to .040 in this case) for better economy, etc..
I never do though.

larrywalk

With a normally aspirated engine and a MSD-6 amplifier, there is plenty of kick in the spark to run gaps of .055-.070. This gets more molecules of fuel in contact with the spark and a more reliable ignition, especially at partial throttle. It makes no difference whether or not the MSD is triggered by points, Pertronics, or a magnetic reluctor.

However, if you don't have top quality wires, cap and rotor, you can have problems due to the higher voltages that larger gaps allow before the spark fires.

landshark 454

If you have a serious coil, .035-.040 will work fine. The MSD box can run wider gaps, depending on coil. Total timing should be 38-42 degrees if you have good fuel, but lower for lesser fuel, 34-36 degrees. Old school curve with good fuel was 10-14 initial, with 28 in the mechanical curve, and all in by 2800 rpm. Lower compression engines can get away with more initial timing, and a tighter curve, and the same total timing.