Eight MPG?!

[TheWhiteElephant]

Aaaahh yes, the old overlooked leaky gas cap. Goes hand in hand with the elusive blinker fluid.

[87 V20 Scottsdale]

I don't think that would explain your lack of power, but it could explain why you're mileage is bad. How does the truck act when you accelerate from a stop?

[justinburnett]

I only get about 10mpg highway. 250, th400, 3/4T 4x4. I don't really think I have much to complain about. It's a big-ass old beater that can haul anything I've thrown at it so far and go anywhere I've wanted it to go. Thought about the 700r4 swap a few times, but every time it comes up, I figure I could probably fill both tanks quite a few times and still come up ahead. Also, I've heard so much bad about those trannys, I know people say if they're built right they can handle a load on 'em but... maybe just superstition or something. Anyway I hope you figure out your problem.

P.S. I solved my commuting issue by buying a 1979 Datsun 210 for $300 that gets almost 40mpg, so I don't really care about spending the extra gas now when I need it. If the truck was my only vehicle I'd be in trouble 'cause I often have to commute from The Dalles to Portland (about 85 miles) for work.

[Number21]

Yeah...I know it's never going to get amazing mileage but I figure it should get better than a school bus. It's not so bad when I think about my old Jeep that got 13mpg with a 6 cylinder and only weighed 3000#. My problem is my 'other car' is a C30!

Originally Posted by 87 V20 Scottsdale

How does the truck act when you accelerate from a stop?

Seems pretty normal to me, just kinda slow. I really need to get a vacuum gauge and see what it says. It SOUNDS like it's running great. It's got a shift kit too, (at least I hope so or something else is broken ) that's supposed to help with gas isn't it?

Several years ago I had to drive a C20 with a 454/TH400 to the DMV....while it was only running on 7 cylinders and I could only get first gear. I'm pretty sure that thing got better highway mileage!

[justinburnett]

Ahh, I thought you said the other one was a C10. Not paying attention.

I can't imagine why you're having trouble getting up hills on the highway. I don't even notice them when I'm driving my truck. Have you checked your compression by chance?

[Number21]

Originally Posted by justinburnett

Have you checked your compression by chance?

Not yet...I probably will when I get time to change the plugs. I am told "the engine was replaced 30k ago", but it seems like every truck on craigslist says that.

My carb looks like it was replaced alot sooner ago than the engine/intake, as best I can tell is its a 600 CFM Performer. Maybe it's not tuned right at all, carbs aren't really my thing. I'm trying to comprehend the edelbrock manual right now...

[justinburnett]

Mine needs tuned too. Running pretty rich. Unless your carb is WAY off somehow I still don't understand why you'd have no power if your engine's in good shape. I know the hp/torque of the 350 engines can be all over the place depending on what you do to them, but it should have plenty of power to get you moving without having to stomp on it, especially unloaded.

Good luck and have fun.

[babyJay]

My 87 30 gets 8 mpg consistently, and it's TBI injected. Doubt the gas cap is going to hurt the mileage very much.