(05-07-2011, 06:59 AM)Rare Pony Wrote: [ -> ]I filled up my 73 Mustang convertible today, which is a 250 CID 6 cylinder, and I'm got 11.1 MPG!!!!! Of course that is all short trips around town. I have always kept a trip diary in the car and even back in the 70's the best MPG I every got was just over 18 MPG! Probably your 302's and 351's get just as good if not better.
Wow, I would expect an inline-6 to get better than 11MPG; even around town. Have you checked some the of things I mentioned above? With mileage that low, I would also look for a fuel leak under the hood. The short, rubber fuel hose which goes between the metal fuel line and the carburetor is notorious for leaking. You might also check that vacuum advance and make sure it's actually advancing.
The way I look at it, if you go out and by a performance car like a Mach 1, you shouldn't be worried about gas mileage cause you knew when you bought the car, it wouldn't be the greatest.
You make a good point, gvervoren. A classic Mach 1 wasn't built with economy in mind and just isn't going to compete with a modern, computer controlled engine when it comes to MPGs.
But consider many things which improve gas mileage also improve performance: a well tuned engine, properly inflated tires, a clean and adequate air filter, free-flowing exhaust and high-voltage ignition, for example. With a few mods and attention to detail, it's not hard to make a classic car get better mileage than it did from the factory. Add an overdrive transmission and the mileage can be significantly better.
Consider also that a Mustang is still a pretty lightweight car. Compared to a Galaxy or Chevelle, a Mustang is capable of squeezing out many more miles per gallon. And that adds up to squeezing our more fun!
(05-07-2011, 09:03 AM)Klutch Wrote: [ -> ] (05-07-2011, 06:59 AM)Rare Pony Wrote: [ -> ]I filled up my 73 Mustang convertible today, which is a 250 CID 6 cylinder, and I'm got 11.1 MPG!!!!! Of course that is all short trips around town. I have always kept a trip diary in the car and even back in the 70's the best MPG I every got was just over 18 MPG! Probably your 302's and 351's get just as good if not better.
Wow, I would expect an inline-6 to get better than 11MPG; even around town. Have you checked some the of things I mentioned above? With mileage that low, I would also look for a fuel leak under the hood. The short, rubber fuel hose which goes between the metal fuel line and the carburetor is notorious for leaking. You might also check that vacuum advance and make sure it's actually advancing.
Thanks for the tips I'll look into some of those. It's been about 5 years since I rebuilt the carb so it may need some adjusting. Could be the auto choke settings too. I believe it should do a little better, but the way I drive it mostly stop & go around town adds to the excess gas consumption.