building a long distance touring car

I consistently got 18-19 mpg at 65 mph from a 351C, torque and mileage cam, 10.3 compression, 600 CFM Holley specifically made for better mileage, headers, 3 speed non-overdrive, 3.08 rear gear. A 318 like that would be my idea here.

• The higher compression raises combustion efficiency; something in the 9.5 if fine IMHO.
• Headers clears out the chambers better after each cycle to get a hotter, more effiecient burn.
• Cam ought to be a 114 LSA, intake duration below [email protected]", modest cam advance, as much lift as you can get.
• Small primary carb like suggested. I used a List 6619 Holley, which was just a variant on their standard 1850 vacuum secondary 4 bbl designed in the 70's for better fuel economy by making the primary cruise circuits leaner.
• The OD trans you have with locking TC ought to give you another 3-5 mpg.
• Use a performance intake, like an RPM Performer. Anything that helps cylinder filling at lower RPM's will boost torque at the lower RPM's.
• I would not hesitate to use better-than-stock aftermarket heads for the same reason.
• HEI ignition
• Add an AFR gauge and tune your light cruise ratio for 15-16 if carburated.
• Rear gear ratio in the high 2's.

The 5.2L fuel injected Magnum is also an excellent suggestion IMHO, with some headers.