98 Vortec 454

OK....here goes. What the heck is up with the timing tables on this truck?

I normally tune diesels (so if anyone wants help with these in trade for help with this PITA) and I used to consider myself pretty decent tuning old - non computer gas engines.

My dad has a 98 chevy 454 vortec and I talked him in to letting me try to get him better fuel milage with it. Told him that with EFI you can change just about anything, just like tuning the oldies. Wellllllllll OK I'm lost. I tried advancing the timing and logged a couple runs and it actually got worse or didn't change a thing....

I'm not asking for anyone's tune......just asking to be pointed in the right direction to achive better fuel economy with out losing too much power. Where I am from we don't have federal emission testing so anything goes for now.

I was wanting to advance the timing thru the whole curve from 1000 RPM's up, above 2800RPM's I was wanting to increase pulse for towing power.

Any takers????????:help2: