Original Author: c.d.iesel
After you remove all the SMOG krap , fit a new mechanical advance distributor, adjust valves, test compression, new plug wires, plugs, ignition timing set using a TIMING LIGHT , change all the fluids, wash and detail the car (that's good for a few more HP's!), and my WEBER 32/36 Jetting Prescription (actually over the counter and CHEEP!)your MPG and performance should improve.
Please purchase ANY How To Tune WEBER carburetor book, many are found right on the Automotive selves of Barns & Noble , or other major book sellers.
The WEBER Tuning book that Pierce Manifold offers is excellent.
...my WEBER prescription:
Float Level 40mm
air correction 145
air correction 175
AND -PLUG THE SECONDARY ENRICHMENT HOLE AT THE TOP OF THE CARB AS MY DIAGRAM SHOWS . DON'T ASK WHY- JUST DO IT AND SEE THE HUGE DIFFERANCE IN ACCURATE FUEL METERING THROUGH OUT ALL RPM AND THROTTLE OPENINGS.