I was wondering how bumping the timing up on the old P7100 can effect fuel economy. If I make the performance adjustment to get more power, will it kill my fuel economy or would it actually help? Assuming, of course, that I can keep my right foot out of the thing!

 

i went from stock timing to 15.5 and it helped mine, also reduced egts a little. it probly helped round about 1 to 2 mpg. this truck started at 18mpg when i got it. now i got the timing advanced a #11 plate intake, exaust and my cruise control fixed, now i get 21. and its a lot faster

 

Adding timing is a fine line of balance.You add enough to make the truck efficent for daily driving as with too much the truck will make power later in the rpm band and make the low end power suffer some.

Street driving without studs and o-rings I'd say that 16-16.5 degrees is about the end of the rope and if your studded and o-ringed then around 20 is good for daily driving.