I have a '77 351-M. I run 85.5 octane through it. I was told with such a low octane fuel that I should set my timing to 6 degrees BTDC to get efficient power and gas mileage out of my engine. The factory settings on the valve cover calls for 12 degrees and I have it at 14...Is this wrong? What should I do? Any suggestions would be great.

 

I would set your timing at 12 like the sticker says. The sticker is correct for any emmissions devices you may have or any other calibrations for your particular engine. If you get pinging, I would try stepping up your octane first.

 

The higher the advance the more power up to a point. With the proper timing, plugs and proper settings so that you don't explode the engine then try higher octane fuel.