Finnaly filled my tank all the way last week so I could test out mileage... Drove it to work nearly every day- Freeway+backroads+ minor Cruising at lunch time.

218miles out of 18.25 gallons = 11.9mpg

I gotta borrow eric's A/F guage and try to dial my carb in a little better.
Can't believe Kevin's 427 gets better mileage than my little 330! :)

My 454 2500 stall and 3.42 gears w/800DP is a super-sucker.
Seems now the mpg is actually UP with the 3000 stall.....
Maybe some single part in your system upsetting the Apple Cart there Rambo....

IIRC you have a good basic tune-up on there....street gears...
I'd think you should be getting 14.5 mpg easily mixed driving and 17 or more freeway/trip mpg

Last time I checked my MPG, '08 Civic 4 dr, 30 mpg, '96 Ram 3500 dually, 11 mpg city/towing, '79 Monza 2+2, 2 mpg :D

I've never really gotten a chance to do any in depth tuning on it. I was real lucky with the 650dp, it ran great with the factory settings when I dropped it on the car. Very possible some jet changes will help.

I need to get it to an exhaust shop to see if the headpipes aren't too rusty to have a bung welded in.. Then i'll be ready for tuning. Maybe at the next BBQ.

My 383 got 12.66 on the way up to Spokane, that was freeway all the way at around 3500 rpms.

Yea I would think something has to be off.

I was going to lunch with a friend today and talking about this, and he commented that i do have a rather heavy foot, and with a Double Pumper maybe i shouldn't be so surprised at the mileage....

Guess we'll see after i can do some tuning on it. Will be interested to see what the A/F is on it.

I was going to lunch with a friend today and talking about this, and he commented that i do have a rather heavy foot, .

You were just showing off. :D;)

Glad your out enjoying your car though. :yes:

Most of your improvement will be in the idle circuit. If your carb is not adjustable then you will need to drill and tap your Idle feed restricter and air bleeds and install drilled out set screws. I actually have the drill bits and set screws if you want to research it and do it yourself. There is a guy on this board that was going to walk me through the process. His screen name is
Camarofever IIRC. Im sure you could send him a PM and he would give you the info you need to do it.

The only reason mine works well is because I paid good money for a carb that was all set up for me. I got the 800DP close but didnt take the time to really tune it like it could be.

Right now my car runs 16.5 A/F at low speed cruise. Freeway is 13.5 and WOT is 12.5 Get your car running the 16.5 at cruise and you will gain MPG :thumbsup:


Ya 12.5-13 MPG and can run an 11.30 :thumbsup:

MPG should never be higher than the fun factor anyways.

I went from a 355 to a 427 and picked up mpg. Newer and lighter technology for the internals.