Originally Posted by ericnova72
70 jet is on the lean side for a carb of that size...the common 750 Vacuum Secondary's come with 72's, and original first 750 Double Pumper was 76's , then every revision after the original was 70 or 71....but the Doubles have a much richer idle and transition circuit.
You may want to read this thread, it pertains to all Avenger carbs and not just the 670 mentioned in the title.....I'd want to do this modifications rather than richen main jetting and possibly negatively affect fuel mileage.
At typical cruise rpms, you are running on the idle and transition circuit and not really the mains unless you are geared pretty deep, 3.73-3.90 or more....so that's why the "lean Avenger idle/transition circuit" thread may be of importance to you.
I read your article and it seems to make some sense. I'm really not sure if I'm still on the transition circuit or not at speed. At 60 with a 3:42 gear, 27 inch tall tire and 2400 stall convertor I'm at about 3 grand on the tach. I don't really know when it gets on the primary circuit. Any help for me?