The Stovebolt Site Forums The Shop Area Engine Shop 1966 chevy step-side

I have a 66 c-10 short step-side;

I would like to upgrade it,the motor,tranny and the rearend if neededand also put ps,pb on it
trying to get better gas milage and speed;;
It has a 250 motor in it now.

What is the best way to do this,I dont wount to change the motor mounts if not needed.
What is the best donner truck that will work the best?
Thanks carl :confused:

You are seeking the holy grail I'm afraid. You can get a little better mileage with an overdrive, a T5, taller tires or shallower rear gear. Now you have to subtract for any accessories you hang on the engine or for any increase in engine size. It takes one part gas for about every sixteen parts air to run any engine, 4, 6, or 8 so any size increase means more fuel. There is one thing that will increase power and economy and that is turbocharging (not supercharging) but we're talking several thousands of dollars. If you can get your 66 with it's brick like shape near the 20 mpg mark you will have done outstanding. I do know of a 64 with the later model 2.8 V6 with all the electronics that the owner is claiming low to mid 20 mpg's.

Like Coilover said, but here are some "typical" upgrades.

1.) Swap over to electronic ignition. You can pull a GM distributor out of the bone yard fairly cheap and this is probably the easiest way to get better performance out of the engine that is already in the truck.
2.) Adjust or rebuild your carb as it can drastically affect your mileage.
3.) Start cleaning up the "little things" on your truck that don't work. What you may find is that all of the "little things" add up to something big.
4.) Keep the 250 but ditch the old tranny. Pick up a T-5 out of a mid-late 80's S-10 pickup or find a donor 700R4 automatic. The overdrive will increase your highway speed without your motor sounding like it is about to blow up.
5.) Find a 70's c-10 donor for the P/S & P/B upgrade. I say 70's because there is an outside chance that you could find a truck with the same motor that you are running which already has the necessary accessories for you to strip and install on your truck. You can go all the way up to '87 I think for the disc brake setup.

If you are looking to really change your whole setup you can run anything in your truck up to a 400 small block without changing the engine mount pedestals. You would simply need new motor mounts and a few other modifications to make the V8 work in place of the L6.

Welcome to the 'bolt!

Believe it or not, but my old black truck got 16.5 mpg consistently, well-tuned & driven like an old man & kept under 65mph-was a 230/3speed/3.73 gears w/nothing except an HEI added. Like Evan said, it had no accessories-no power anything & no A/C, tall skinny OE-type tires. I got 16mpg w/my other 64, 350/700R4/3.42 gears. Brian

as for the power steering and power brakes you will need parts from a 73-87 c10 pickup (watch out in the 80s they switched to metric?). you will also need a few other parts to complete the swap. for the power steering you will need a REZ kit which you can find from many vendors or google search it. for the disc brakes you will need new tie rod ends and upper ball joints to adapt to the newer spindles. this would also be a good time to replace your springs, i wish i would have... i have done both of these swaps on my 63 but opted for newer parts rather than hitting the junk yard. good luck and welcome to the site

Like you, summer, I also have a '66 shortbed stepside.

I swapped my 250/3-speed/3.73 rear gear for a mildly built 292/NP833 overdrive (kept the 3.73). Mileage is actually worse even though I can now cruise at 80 mph at lower rpms than I previously did at 60 . Could have something to do with the 500 cfm Edelbrock 4 barrel carb (ya think?). :rolleyes:

I believe that a great combination for this truck (if I had to do it all over again) would be to keep the 250, put in an RV type cam, do a spectacular port & polish of the head, 2 barrel carb with Offy intake and Stovebolt headers. You would have plenty of extra "oomph" to run PS & AC, and enough low end torque with that cam to get a strong start off the line. Your gas mileage would be about the same as stock.

-ftyler