Gas mileage???

[RITTER]

So after my quadrajet rebuild I filled my gas tank up, I drove 100 miles and filled it back up, I am getting 8.4 miles per gallon Why can't I get better gas mileage with this thing :?: It is completely stock and balless :!: I have a feeling this SBC is going to be the one that makes me hate SBC :? I wanted to keep a spreadbore to hopefully get better fuel mileage, doesn't seem to be happening.
What kind of gas mileage are y'all getting? And what intake and carburetor combinations are you running? Cam? Filter? anything that has to do with fuel mileage?

 

[beermonkey9417]

im hoping for anything over 10mpg :lol:

 

[RITTER]

Well I wouldn't mind getting 8 miles per gallon if I had 500hp

 

[85 Cutlass Brougham]

I get around 14-15 mpg with the combination listed in my sig. That is using the car to deliver pizza, not driving it on the highway. However, my combo is optimized for my car and for pizza delivery. This means it is geared for the engine and the engine is optimized for low to mid range torque. I do run a Quadrajet, but I spent the time to set it up properly. I also chose the right carb for the job. Using one from a larger engine than the engine you have can make it run stinky rich all the time. I have a 355 and run one off a 350. If I had run one off, say a 500 Caddy, there would be nothing I could do to make it run lean enough because of the idle feed restriction being sized too large.

 

[RITTER]

15 mpg is all I am really expecting to get

The carb is from a '78 350 Chevy and my engine is a '73 350

 

[pontiacgp]

if your getting 8.3 mpg I'd be taking that carb back to whoever rebuilt it...have you looked at your plugs yet to see if it's burning rich?

 

[RITTER]

I rebuilt it myself "Quadrajet Rebuild" thread

 

[FE3X CLONE]

My old 455 with an aluminum intake and 850 mechanical secondary Speed Demon, TH-2004R and 3.73 gears would get a combined 11-12mpg.

My brother's 403 with bigger cam, headers, intake, 750cfm vac secondary Speed Demon, same trans and rear gear was in the 12-14mpg.

I'm guessing somethings messed up with your carb.

 

[RITTER]

I'm thinking something is very messed up :!: I am about ready to trash the quadrajet and just go with an out of the box Edelbrock 1406 or something, I would rather not but I can't seem to find anyone local who really knows quadrajets

 

[crash]

What about your ignition timing? Too far advanced or retarded will kill your mileage and power. Pull the plugs and see what they look like.

Is your exhaust ever black?