[davepl]

I like those original 2bbl carbs on those, they run well and are economical. I would guess yours is wildly out of tune.

Properly set up I imagine you should get 12-14mpg in the city and maybe 18-20 on the highway. There will always be heroic tales of people getting 30mpg and so on but I'm talking about normal driving.

You must have something fundamentally wrong with the carb. That's a good thing, because it can be fixed!

Also the easiest way to calculate mileage is to fill it, drive 100 miles, and then refill. Don't try to measure consumption (as opposed to refilling), it's too inaccurate.