That makes all the difference, I only get 14 MPG driving around Pender Island. Speed limit is 30, no flat land anywhere, no straight roads anywhere, first gear is very low, a 373 rear gear and 464 cid doesn't add up to good gas mileage.

It's not the actual MPG numbers I was commenting on but the fact if was lower with the larger camshaft. Whether it was 25 MPG or 15 MPG wasn't the point, just that it was higher with one cam and lower with the other. Cars move due to the engine's torque, I got more torque with the shorter duration camshaft and more horsepower with the longer duration camshaft. Peak horsepower was higher with the bigger camshaft but at a higher rpm. I didn't drive 3,000 miles at 5,800 RPM which is where the higher horsepower was. The smaller camshaft had more overall torque and at a lower rpm than the other camshaft. I did drive 3,000 miles at an rpm mostly between 2,000 and 3,000 rpm.

I'd be interested to know what a bone stock 68 400 with a 066 camshaft would get for MPG and then what it would get with a 744 or a 041 camshaft, traveling the same 1000 miles or so at the same speed and conditions.

Just wonder, don't know why these things interest me but...

Ramair68: No secret, just an engine with a lot of torque and a five speed tranny with an 0.68 overdrive. 70 MPH is just over 2,200 RPM. One does have to have the torque to move the car at 70 mph over a 4,000 foot mountain pass at that low an RPM.