1967 Buick 300 V8 fuel economy RPM sweet spot?

[wireb]

I am working on a 1960 Willys delivery that has a 1967 Buick 300 V8 installed in it by a previous owner. Need to swap out some bad axles (Found the rear housing bent and front is cracked). Since I am looking for new axles anyway might as well set things up to optimize engine RPM at highway speeds. (I will be taking it camping) Electronic ignition with a MAP sensor is already in the plan.

So the question is what RPM range on a stock 300 is best for fuel economy at highway speeds?

Thanks,

[WildKitty]

I've run my 300 (64 LeSabre) on the bench, w/tranny attached, and I use a vacuum guage to determine the "sweet spot" for the tach. However, once you drop it into the 4,000lb car, you only have a starting point. A nice long run, listening to the exhause and watchinng the vacuum guage, you can find the optimum speed to set the speed control. on my Wildcat (445cu), optimum is 67 MPH. I measurred over a 300 mile run, and got 17MPG.

The vacuum guage is my favorite guage/tool
64 LeSabre, 300cu
64 Wildcat, 425cu
67 Impala, 327cu
Buick 455cu on bench

Butch