Fuel milage

[69GMCLonghorn]

Originally Posted by UltraBlue71

Q-Jet x4

He should put 4 Quadrajets on it?? Isn't that a little overkill for a small block??

[67ChevyRedneck]

My comments were based on everything being in a truck and about a truck. Why would I care what a firebird with the same engine got? I'd assume that for the sake of common sense we were talking about the fuel mileage of a truck.

[project 67 sub]

dont understand exactly how but im averaging about 17.5 miles to the gallon on the freeway doing about 65 in my burb, and 6.5 around town driving like an old lady

[big mike71]

I get 8 mpg, If I was worried about fuel mileage I would buy an S10.

[CSGAS]

For around town traffic, stop and g stuff the biggest impact on your fuel mileage will be weight, especially rotating weight.

Lighter wheels, or wheel and tire combinations, along with regular lightening tricks will help. If you were doing long freeway runs, with open roads and little to no traffic, you would want nearly the opposite--heavier rotating mass would carry your momentum allowing you to coast more.

The Q-jet, or another spreadbore carb, gets another nod from me. So does the Multi-spark ignition, you can get boxes for as little as $175 new that may not be drag strip heroes but improve cold-starting as well (even with points).

Choosing a trans that matches your torque peak to the speeds you drive most also helps in traffic in particular. Since you already have a 3.08, I'm thinking a 5-speed or at least a 4-speed so you get gears you can use stoplight to stoplight. If you have to have an automatic, the lower rotating mass gives the nod to a TH-350. If you want an overdrive tranny you'll never use the OD unless you change to 4ish gears.

I always found about 62 MPH to be the speed (American) that I could get the best gas mileage. There seems to be a balance there between mechanical resistance and where air resistance takes over.

To improve aerodynamics, make sure the window frames line up with the door jambs tightly (roll down windows while adjusting this), close up body gaps and hood edges. Seal whatever you can. If you can hear a whistling noise, that's air passing through a restrictive opening, fighting your truck and slowing it down.

When you are ready to spend a couple dollars, converting to a truck/RV profile hydraulic roller cam or engine should be less expensive with more satisfying results than TPI.