I just checked the mileage on my car for the first time in at least 10 years. 10 years ago I got 12MPG around town. Since then there were many changes. Some cancelled each other out but in the end I have a more efficent combo. The changes are: portmatched intake and heads, bigger valves, a little more compression(due to the new valves),1.6 roller rockers, a recurved dist, a holley 750 dp, a 3.73 rear and a 200R4 OD trans. I was guessing I'd get around 10 or 11 but I was very happy to find I got 13.22 MPG :TU: I did not baby it but I got into the secondaries very few times. The traffic here is way way way worse than it was 10 years ago. Stop and go with 45 and 55 speed limits. Basically running light to light. I wonder what she can do on the highway. I got a real 19.85 MPG all time best after my 1988 rebuild but I don't think I'll ever see that again. Of course speed is my priority but getting decent mileage is always a bonus :3gears:
I've averaged right around 12 mpg with my current setup. I'm swapping a 200R4 in the car in the next couple of weeks. I'll be interested to see how much it picks up. I'm guessing maybe I'll get to 15 mpg or so. Of course now I'll be able to cruise at 80 mph or so, so I might see no increase.
In my 65, the 455 is a stock unit from a 71 Electra, carb is an 800 CFM Quadrajet and the tranny is a 200R4. Most of my commute is highway and I average 17-18. If I stay out of the secondaries, I can pull 20, but what fun is that.. Keith
I had a best of 23mpg on the way to Flint in 2003, but I probably get an average of 16 hwy, and 10 city. I can't get enough of the fuel:Brow:
With my 350-4 ,th350 2.56 combo I averaged about 14 on the highway, and 10-12 on the street. that was with out vacuum advance. When I put the 430 in, same tranny I got abut 8 city, and around 12 on the highway. When I put the Quadra-jet back on I got 15 on the highway, and about 13 in the city. I was very happy. :beer
I've got you all beat :Brow: 27-30+ mpg The only race I'll beat you guys in is a "How far on one tank Race" 0 to 60...in oh...about how long it takes the lighter to pop out. 1/4 mile time....depends on if I'm going down the hill to the market, or back up. Engine specs: 215 Alum V8 2 bbl Modifications: New plugs and wires and one can of degreaser. Been raining lately so it's the one time of year I can peel the tires...lol :3gears:
i get 8mpg with the stock one legger rear, th350, 350 engine all original except the 600 AFB with a 1'' adapter/riser. points distributer all of that. but personally i dont care about gas milage, she makes a good runner for long trips, with enough fuel that is! this $2.00/gal+ crap has to go though!! DIE OPEC DIE!! p.s. not a daily driver, for the obvious...she was when i was making more money, bad wear and tear though!
On my 1970 Stage 1, I've gotten 18.6 mpg at 70 mph(no,I'm not kidding).That is with the 3.64 gears and turbo 400 trans. My 1987 GN gets 31.4 mpg @70 mph.(I got that on my way to and from the GS Nationals last year). Who says you can't have a musclecar and enjoy great mileage too?
Last year on the way to to the BPG show in Ohio I got 18+ MPG with my stock '68 GS 400 w/2.93 gears traveling at an average speed of 65. :beer
I get about 13 around town. I used to get 16-17 on the highway cruising about 80, but then I detuned it to run on 89 octane and it went up to a little over 18. Maybe I'm just going easier on it without realizing it.
Beth's wagon got 13.96mpg with the new motor on the trip back home from Salem last August. 419 miles 30 gallons used. Purred like a kitten at about 80mph and 3200 rpm the whole way home :3gears: I expect its mileage will increase a great deal with the addition of the new trailer though. :Brow: The suburban's mileage is another story D.
:shock: My stock 70 GS 350 Th-350 3.23 posi will get 17 MPG if I treat it nice! It has the original Quadrajet and an HEI. Do you drive with the secondaries open??
actually joe, im expecting a letter from the city complaining about all the ricer doors i leave in the street after i blow them off!!! :3gears: i cant help it, i usually baby the car but when the time comes ive got a heavy foot!! also my theory is that quadrajets get better milage than square bores because of the massive secondaries. i think they use less fuel in the primaries because you can dump a massive amount as soon as the secondaries are open. so with this AFB(holley) im probably relying on secondaries a lot.
I have a GN and an old trick is the paper clip or lock up switch. It is supposed to additionally & manually lock up the convereter in 2nd and 3rd to be good for at least 1/10th & 1 mph in the 1/4. (BTW this held true on my car) The 2004R is already supposed to lock up the converter in OD. I did this and noticed that it not only would drop the rpms in 2 & 3rd but also in OD. Huh I though OD was supposed to lock up automatically. Never checked it for a fuel mileage gain on the interstate but I bet it is there if used properly with enough interestate driving to measure it. Anyway I have a Big Block G-body that I have installed a built 2004R into and have recently added a manual lock up switch. Same thing rpms drop about 200 rpms even in OD. Naturally you must flip the lock up off or it will eventually lug the motor if you are decelerating. I am curious if anyone else has expiermented with this and or thoughts or concerns with doing this. I plan to test for mileage this summer and see if I get a difference useing the lock up on the highway. This is definately not something GM could for the general public but its proven to be usefull at least at the track. Its harder on the converter but its not like you use it constantly. The converter in the GN was the stock D5 and behind the big block a quality rebuilt 2800 stall D5. Oh yea mileage on the GN is normally about 22 mpg (if I can stay out of it) with a mix of hwy & city. With the big block I just hope I can pull down 15 mpg on the highway. My thoughts is hey its as much as most of those sumu sizes SUVs.
