Bigbadswingdaddy, my street rod is a '32 Ford highboy roadster, not a pickup and it really does get over 20 MPG at a consistent 70 MPH on the highway. I built a similar engine for my son's '78 El Camino and it has the same lively performance and about 19 highway MPG with a 4-speed Sagnaw and a 3.08 rear gear. With its 3.80 rear gear and .67 overdrive ratio my roadster engine is just running at a fast idle at freeway speed in 4th gear. The camshaft in my roadster engine is a Crane piece with duration at .050 of 218* and 230* yet it pulls that overdrive ratio easily just as the Crane tech guy told me it would when he recommended it for my application. It also revs up enough to really press me back in the seat make my eyes water when I merge onto the freeway.
I know other street rod guys with even better mileage numbers but they have EFI, not a carburetor. Getting optimum performance requires doing more than simply buying a crate engine and taking parts like a distributor and carburetor out of their boxes and installing them. There is a lot of power and fuel economy potential in matching compression ratio/intake and exhaust port volume/intake manifold design/camshaft/header design/exhaust system design and in fine tuning carburetor calibration (primary main jets, secondary main jets, metering rods, metering rod springs, accelerator discharge nozzel orifice size, etc) and distributor calibration (initial timing, mechanical advance curve, vacuum advance curve).
The point I was trying to make is that if a person is willing to research the subjects of precision engine assembly and tuning and take the time to optimize a combination of engine parts the results can be very good. I've discovered that most casual street rodders cannot resist the temptation of instant gratification and opt for a "crate engine" with "out of the box" accessories.
I'm always looking for "speed secrets" that others have discovered and friends who are racers love to talk about what's inside their engines and what they plan to try next for better results at the drag strip or on the Bonneville salt flats. There is no such discussion with the "crate engine" guys because they don't know and don't care what's inside.
To each his own, right?
