OK if you need to spin 3000 in third to go upa grade with your current tire size, something is wrong. A big block should be able to lug that in fourth easily.
Wow that's bad.
I agree. My 440 74 power wagon pulls like a beast in fourth going up a hill with 33-12.50-16.5's. It's mostly stock. 40 over flat tops, edelbrock performer intake and street avenger 670 carb (what I had at the time that worked).
Fuel mileage is roughly 15mpg. If I drive it like I stole it, I can guarantee it'll get about 8. But I have a heavy double return spring on the throttle. Keeps me out of the pedal.
Good luck with that 400! I hope you get it sorted out. A big block 2wd should be a hoot. No reason a 400 shouldn't perform well. If it were me, I'd throw some Pistons in it. Raise the compression. Without compression, your choices are limited.
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