Geez....you drop by once a week and this is what's getting everyone excited. Well, here's my 2 cents:
13 MPG on that engine sucks. I agree with the "Dan and Stan" team: It's mostly in the idle jets, but we don't know what you've got for intake and exhaust systems or even what you're running for an ignition. all of that matters, big time.
Like Danny (and I'll cut and paste his stuff here and correct it for me cuz I'm basically lazy on typing):
I have a Type1 2110cc, Dellorto 40mm (best carbs on the planet), Engle 120 cam (hot street), stock rockers, 44.5 X 37.5 valves, and CR is 9.0:1. 160 mains (yeah, I know they're rich, and I like them that way), 55 idles, 180 air correctors, F11 emulsion tubes and 38mm venturis AND it's been converted to horizontal discharge tubes. 150 hp estimated, but in a 2000 pound car, it don't take no guff from anyone. At turnpike speeds and on the mains, my air/fuel ratio sits like a rock at 12.8
In addition, the intake manifolds are matched to the heads, the heads are ported elliptically and both were finish polished by me. I'm running a Berg extractor system (DP932) with dual quiet pack mufflers to balance intake with exhaust. EVERYTHING was carefully matched during the design phase. What you run for an exhaust is just as important as what you have on the intake side.
I get about 26mpg in mixed driving and it reaches 30+mpg on sustained 75mph interstates.
My gas tank can be stuffed with 8.3 gallons and will give me a consistent 240 mile range on a trip.
I agree with Stan: Pull your carbs and send them to Art Thraen and get them set up right.
gn