Quote:
Originally Posted by Purcell69
It can be done depending on how aggressive the cam is and what your overall gearing works out to relating to engine RPM at highway speed. At 9.375 MPG, you would be bone dry at the 300 mile mark.
I've had two 454 powered trucks that would consistently get me 12 mpg. One was a bone stock 1994 C3500 with TBI. The other was a 1978 C10 using a 454 I'd built, hooked to a TH-400 automatic and a 3.07 geared rear axle on 31" tall tires. The carb was a Holley 3310 750 CFM vacuum secondary carburetor with the heaviest secondary spring Holley offered to keep the motor as lean as safely possible. The motor was built for torque and towing so it didn't need to spin fast.
4wd may cost you a bit, but the lighter truck body may be enough to offset that, hopefully. It's going to be close.
-Joe
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I built the motor for low end torque too. I used an "RV" cam from summit, and a 750 cfm vacuum secondary carb. I doubt this motor will ever see over 5000 rpm. I have an SM465 manual trans, 4.10 gear axles and the tires are a tiny bit over 33". The 205 transfer case is part time, and the front hubs lock in or out, so I won't be spinning the front axle in 2wd. I should be able to drive it comfortably on the highway. I may eventually swap to the NV4500 trans to get an overdrive 5th gear, but that would be after the truck is running and driving if I ever do that.