I have build and modified many Qjets over the years and want to say I know exactly how to tune this carb. The same goes for timing.
So my Qjet is modified and I have found the best jet/rod combination for it giving the highest mileage optainable with the best throttle response and power. ( the leanest setting possible with out hurting power )
Timing is bumped up to 17 initial with a 33 total. vacum advance is 15. all in by about 3000.
If one knows his SBC timing, he will know that these are close to perfect numbers for a mild 350.
The problem is I just cant get mileage above 20 mpg. This is based on consistent 50 mph driving.
The car is a 1979 Caprice with the LM1 170 hp 350. completely stock but with a muffler were the cat was and 2.5" pipe all the way to the rear bumper.
I had a ´79 Caprice with a stock 305 once, and that thing was able to hit 21-22 mpg average.
I am making sure I know exactly how many miles I drive. I dont just go by the odometer. its inaccurate.