At one point I played with that system in an 88 Cadillac Fleetwood with a vin 9 307. That car had a 180 hp 307, 200-4r and 2.53 gears. 27 mpg but no power on hills. Was gifted a solid main 403 out of a late 70s GMC motorhome that I helped put a 500 cadillac into. Put a set of earlier 70s olds 350 heads on that 403 along with a mondello cam and an edelbrock intake. Car would get 25 mpg and never slowed down. Was able to get it to run well without tuning the ECM although later made some small changes to that 830 ecm.Originally Posted by Jim_Rockford
My old 83 G20 with a mechanical q-jet would often get 20-21 mpg highway. LE9 305 with flat top pistons and 601 heads and factory catless dual exhaust with factory tubular manifolds off a 1-ton 350 van that I had added a dr gas x-pipe into. Van had a 700r4 and 3.08s.
Still like my old school q-jets. Actually just finished completely rebuilding a virgin 84 305 G20 carb that came off a van nearly 20 years ago in the wrecking yard. Rebrushed the shafts, removed and resized the idle down tubes, resized the idle channel restrictions, resized the idle air bypass ports, resized the idle mixture screw holes, resized the accelerator pump holes, resized both the secondary pull over enrichment ports as well as the pull over well restrictors. Then changed the jets, metering rods and power piston spring. Finally resized the needle seat and created a new seat for it and the accelerator pump check ball. New secondary hanger cam and windup spring also installed. Removed the choke plate, shaft, and linkage but retained the thermostat and fast idle cam. Started chokeless as soon as fuel reached the fuel bowl, settled to a high idle and just ran great.
I clean my carbs in a heated ultrasonic bath. All kinds of dirt, dried gasoline, carbon and crap come out of the carb.
The one I built running on my 11:1 aluminum head, roller cam 383. Actually ran 8 minutes and 36 seconds without a load at 2,000 rpm on 1 quart of fuel.
https://youtu.be/l7XDuEvqFR4
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