What do you think of my MPG?

[fstfwrd]

A quick easy start would be to disable the lockup feature of the torque converter. You will still have overdrive for going down the road, but you will gain 200 to 400 or so rpm going down the road at highway speed. If you decide to do this, I would make sure you have an external tranny cooler, or even a tranny temp gauge.

I don't think having the converter NOT lock up is going to produce enough heat to murder the tranny, but any way you can cool essential fluids it would be wise to do so.

leftybass209, I've sold Edelbrock carburetors for several years to guys that have leaky Holley carbs on their old farm truck that is lucky to see a thousand miles in one year. We have a shop and perform repair work as well. While they are relatively easy to work with, you get an old C60 truck with a tall deck 366 or 427 big block Chevy, and they will not run for ****. It's nothing to tune it so it idles fine, but then you have to deal with the actual driveability aspect of the carb.

We stuck a 204/214 cam in a 1968 Chevy 307 V8, then mated it to a lockup turbo 350 trans and installed it in a 66 C10 pickup. 3.42 axle ratio, when the converter locked up at highway speed the aftermarket tach would read 2700 rpm. Obviously not a mile per gallon highway cruiser. But that particular carb had warm start issues, my buddy was always fighting high idle issues (nice feature up here in chilly North Dakota). In the end, I installed a Quadrajet with a few minor tweaks in place of the 1406 Edelbrock. The 307 idled better, the idle surge was 100% eliminated, fast-idle worked great on cold mornings, and he ended up getting better mileage on his 30 mile round trip to work everyday.

I wasn't trying to start a heated debate, I've just dealt with these carbs and figured I could share my experience in using one and modifying if needed. The 600cfm seems a little awkward on a mid 70's tall deck 427. Adjust and tune to your hearts content, but there is a HUGE tradeoff between just getting the damn thing to idle, or driving down essentially lugging the engine with a full load on the tandem axle truck. Not that it matters in this conversation, but the factory C60 etc trucks had a Holley carb set up for use with the PTO to run the hydraulic pump to lift the box. The customer complained several times, and after several adjustments, we finished the job by putting a kit in the stock Holley. Again, driveability was better, it idled about as well as any worn out big block Chevy, and the customer claims the fuel mileage went up some.