When you put the true TDC timing set in did you have to do anything computer wise? or did it just adjust settings on its own?

 

The early timing set pull the cam timing back about 8 degrees (advancing). You will need to reset your ignition timing after the chain change.

The cam timing change will open the intake valve earlier and increase cranking compression and also increase torque in the lower rpm range.

Also the change will help fuel mileage, but maybe not enough to notice. But the extra torque will help the 3.55 gear change increase mileage.

Headers, full big tube exhaust, with free flowing mufflers, and silencer removed from air intake, along with a free flowing low restriction air filter will also help. Highway tires, driving style, And if your not towing, you can mill the heads some to increase compression.

All this and I doubt you will see over 14 on the interstate even with a 3/4 ton 4x2.

 

A good thing to do if not done already would be to remove the restrictors in the intake tubes coming from the filter. I was getting 13 mpg from my 460 with 4.10 gears, c6 trans, and 265-75-16 M/T's on a 4x4 one ton. Removing the restrictors will also give you a slight power gain. Nothing serious, but it is noticable.

 

I used to get 11.3 in my '78. It didnt matter what I did, either! Loaded, unloaded, towing, or not! It seldom changed. Sure moved, though!