How many miles on a tankfull are you getting with your quadrajet?

 

After rebuilding and re-adjusting the CCC-Q-Jet, replacing the 02 sensor, a good tune-up, and replacing the plugged factory cat on my 1988 Cadillac Sedan Deville Brougham with a 307 9 Vin (over 300,000 miles), 2004r, 2.53:1 gears, P225/70/R15s, with a 28 gallon tank would go nearly 700 miles before fill-ups. I don't see why a stock LG4 would not get 25-30 MPG highway(at a constant, decent speed, with the cruise control on) in good tune.

 

I only get about 250 miles on a 15 gallon tank.

 

you are getting good mileage berlin.

I got just over 200kms on a tank, and I think that was about 20MPG, with my non overdrive LG4 setup.

 

13-15 city
21 highway

 

Well I thought I was getting bad gas mileage. Guess thats all I'm going to get with this carb. How much of an improvement would I get if I fuel injected it?

 

Last time I filled up, I had put in a few gallons inbetween to tide me over at the track. So, I went 404 miles between fill-ups. There was stop & go, highway, and 10 1/4 mile passes included in those 404 miles. Took 20 gallons total for 20.2 MPG. That's a little over 300 miles on a 15 gallon tank.

I've recorded as much as 27 MPG on straight highway miles.

Sonic, something is wrong with your figures. 200 kilometers is 124.27 miles - if you used 15 US gallons in that distance, that's 8.24 miles per gallon.

 

my L69,5spd. 3.73 trans am used to get 13 city 18 hwy if i took it easy on the pedal

 

on my 85 i see about 300 in between fill ups and i only put in about 11 gallons in when i fill up so i seem to be getting some descent milage... the funny thing i get the same as my girlfriends 02 mercury cougar v6... she hates it... lol

 

Per tank is a lousy measurement of fuel mileage. Please measure mileage in MPG.

That said, my mileage for my thirdgen was 19.5 city and 24.5 highway. I was running a ZZ4 crate on the full computer setup, '84 sport coupe (no gfx), '95 T56 trans (0.5 6th gear) and a 3.89 Ford 9" rear axle.

 

14 city/ 21 Highway with 5sp and Quadrajet'd 305 -- pretty sucky.
Oh yeah, I've also got the 3.40 rear end.

Anybody know if headers/high flow cat etc makes a difference in mileage?

 

Yes, freeing up the exhaust is an excellant way to up the mpg numbers.

The more efficent your motor runs, the better milage you shall recieve.

Although, I have found the biggest gains while I had a (temporary)reduction of right-foot leaditis. Keepin out of the throttle makes a huge difference.

 

Back when my '84 was stock, I kept track of fuel mileage for every tankful from 1990 through 1998. It was a 3.73:1 rear gear, 700R4, 305 H.O. and on the highway I got 20.5 to 22 MPG, and around town it was 16 to 17 miles per gallon.

Pizza guy is right though - If you granny the car and always stay out of the secondaries, you can net great gains in fuel mileage, typically 3 to 4 MPG.