I timed my 261 right on the BB and was not pleased with my fuel mileage. I decided to experiment with the advance (since that is easy) and I have ended up almost at the end of the advance slot. I run E-10 gas exclusively.

I can get my motor to ping when 'lugging' around a corner, say around 1200-1400 rpm. I suspect that if I put in heavier mechanical advance springs I could get this problem to go away. I only turn 2000 rpm going down the road 68 mph and I really think I need full advance by 1700-1800.

I have not taken my pickup on a long enough trip to check highway fuel economy since advancing the timing, but it seems like I have to fuel up less often around town. I try very hard NOT to lug the engine in the rpm range it pings in. Even with the timing at this level the engine NEVER fights the starter. I noticed that the tailpipes are burning gray now rather than the black when the timing was on the BB.

Remember 9-11-01--God Bless the USA
JUSTICE, not REVENGE, will prevail

1951 Chevy 1/2-ton Pickup truck