I ordered that dual plane for 133.00. Cheap enough. I have my torgue convertor clutch running through a toggle switch and then through the brake switch. I used the Gil younger shift kit and I keep it in 3rd till I get going fast enough to shift to overdrive. Alot of times I keep it in 3rd because I don't go any faster that 40-50. I don't want overdrive coming on going that slow. The tcc works after 3rd and 4th winds up a little like it should. Took a couple of times changing springs in the valve body to achieve this. I can pull all that about 80 MPH But I'm getting into the 4 barrels a bit. I have the jets just above the lean side so maybe 1 more size up might help to keep it in the 2 barrels going that fast.
I had an '83 Suburban 2500 454/th400/3.73 that got a solid 7-9 mpg towing our 28' enclosed. I know pulling up the big hill in St. Louis it would slow down to 45mph and hold second gear going up. The trailer was quite full 10k limit so let just say 9999#. We have since upgraded to a '99 with the same combo except the 4L80e. Much better mileage except when towing but it did get us up to 9-11mpg towing. It has gotten 15 mpg on trips loaded but not towing running 70 mph on the open flat hwy. Our '94 has the 5.7/4l60e/3.42 and it drops down to the 10mpg range towing out open car hauler but get 17 mpg in mixed driving. I wouldn't try to tow our big trailer with it.
I just intalled the Pro Comp China dual plane intake on the 454 and it seems to run easier on normal accelleration. I put 10 dollars of gas in it so I might drive it to work 1 day this week and see how fast it uses gas now. It still has the problem of flooding if you don't have your foot on the gas at start up. Since I rebuilt it It floods as soon as it fires. I have the fast idle set right and the choke pull off was new and adjusted. Once it starts I can let off the gas and it runs fine. I've rebuilt alot of Qjets and this is the only one that has done this.
adding a turbo to the old 6.2 been the best bet that or find a 12 valve cummins. but ill agree a od would help it.
