can a pontiac motor be made to get good hiway gas mileage? steep gears and tall tires maybe? or what would happen with a overdrive transmission? any one getting decent mpg now?

What's decent? I used to get 16-17 mpg at 70 mph with my 068 cammed 400 with the TH400 and 2.56 gears, and 14 mpg at 85 mph with an 041 cam, 3.23, and 4 speed.
I always was of the opinion that Pontiacs gave pretty good mileage, as my buddies with their TA's regularly knocked down the same mileage under similar conditions.

After my carb was rebuilt I got 17 mpg, 2.93 rear, 400, th-350.

I've heard of people up into mid 20's to, then again thats jus what I've heard.

1964 GTO with tripower - 22 MPG highway at constant 70 MPH. sold car a few years ago. Would guess mileage today (with ethanol) would be 19~20 instead.

Jon.

2.78 rear, 700-R4 overdrive, 9.2:1 350 with 4 bbl

The one time I measured carefully AND pushed lightly on the go-pedal, I got 22.9 mpg at an average of 65/70 mph. I'm sure I could tweak that with a couple more psi in the tires and doing 55/60 mph.

That was all highlway mileage. I'm not sure what around town is. Maybe 15 mpg?

My 71 Gran Prix had a stock 400/300hp. It would get 21-22 on the highway with four people in it and the a/c on. Don't know what gears it had though. Barry

my current 400 w th350 and 2.56 (and a 650 Holley) gets 15 mpg on freeway at 75- 80+_ and about 9 in town (having fun!)

Mine is in the same range as Bjorn's with the 2.73...but generally to the low end! That's with a 400/TH400. I just did a shift kit, and haven't put on enough miles to determine if there is any improvement in economy.

Gas mileage is generally poor until the engine reaches full operating temperature, so if you do only infrequent short hops your mileage will suffer, and it drops a couple of mpg if I use the air conditioning.

Use of the air conditioner did not seem to effect the mileage on my tripower GTO; however the appearance of a Camaro or Mustang would occasionally effect the mileage (generally less!).

Jon

Jon, I know how that does it!
So did a BMW M3 affect mine , when he was trying to show off next to me yesterday! but he gave up halfway thru his second gear! he was still just behind my rear quarter.... guess he didnt want to look ridiculous...

so Vikki, how does the shift kit feel??

Funny how final drive ratios are all over the place for these birds!(I have 3:38).
I once was bold enough to check the highway mileage when I had all my performance gear on my 400: cam, headers, double pumper, single plane, etc.
I got 12.
Now that I'm going back to stock I'm hoping to get the kind of mileage y'all get, but I don't want to change my original 3:38 posi.
Havent heard from the OHC6 club yet- I bet those have great mileage!

My '66 Le Mans Sprint pulled down 18.8 mpg on the highway trip home from Wisconsin (3.23 rear, 2 speed auto) and averages 16 around town.

It's been many years since I checked it but if I recall when we took it on vacations it would run in the 16-18 range. The 2.56 would let that 400HO run at a fairly low rpm at high speeds. At that time it was real leaded premium fuel too. So a lot of the milage robbing stuff in gas today wasn't a factor. But around town and with many fast starts it was much more thirsty.

Don't know if any of you have ever noticed but I've always thought that the long needle and wide travel on the Bird's gas gauge, relative to most vehicles, makes it appear to drop faster.

Mine did average 17 mpg on a 900 miles trip. Was doing round 60 most of the time. Rpm was close to 2000. 350/265, now with a q-jet TH350 and 2,78 rears with 225/70-14 rubber.
Feels a little high. Might look into that in the future..... :rolleyes:
But .....it really doesn´t matter too much; it won´t be driven too much up here. And gas is some 6.50 bucks a gallon!!!

You are all lucky, or smoking crack. I dunno which, but I'm getting MAYBE 10-12 MPG in my '68. Car runs fine, no smoking or wierd stuff, idles high at 1200 or so. At 2.59 a gallon for HT this is starting to hurt.

Nash, i totally agree with ya! I'd smoke crack too if i got that kind of mileage I wish i got my gas at $2.59 u.s a gallon, Paying a $1 a litre here, 3.79 litres in a gallon. I'd get more gas for my money down south This gas price crap blows.

David

Over here gas is close to 5$ a gallon.

how do you guys afford gas at those prices? do people just not drive as much in other countries? or do you guys make more money to compensate for the high prices?

In order to afford riding the thirsty old bird of mine, I'm trying to cut down on food, (which is probably a good thing...)

/goran - paying $6/gallon, 70 per cent taxes...

38% of our gas price is federal taxes and you know how the the government is once they have their hand in your pocket.

David

In Europe US forces get gas coupons. Here, depending on the euro and the monthly rate, gas is about $2.50 a gallon.

Everyone else in Europe has a car that gets 25 mpg on a bad day. A big engine here is 3L, the new Ferrari 612 ($250k +) has a 6L V12, and the 430 has a 4.3L V8.

My OHC-6 cars are not stock, but my 69 Sprint Bird (301 stroked OHC-6) T-5 with 4.10 gears got 22.5 MPG at 70 mph and 17-18 in the city.
My stock engined 66 Sprint Lemans 2004R with 3.90 gets 24 with the A/C off at 70 MPH and 22.5 with the A/C on. and about 15 MPG in the city.
I added the overdrives mostly for cruising on the highway and in the case of the automatic Lemans to get rid of the miserable ST300 that along with the OHC-6 engine & stock 3.08 gears made driving the car a miserable experiance. You will never make up the $$$ spent on the conversion with the increased gas milage, But it does make a difference with the steep gears I tend to run.

Jeff R

This might help you feel better about your mileage. I drive a 2004 Ford Excursion 4x4, with a gas V10 powerplant. I get 10.4 mpg, uphill, downhill, pulling a boat or not pulling a boat, with a headwind or tailwind, city or highway, with 7 people and a dog, or just me driving....10.4 mpg.

Fish on

I have a Dodge Durango and a Dodge Ram 1500, both 4x4s with 4.7L, and neither will get better than 16 mpg highway. Last tank in the 'bird, 6.6L, lead footing it around town, got 13 mpg.

Crazy Tasty, I spent 14 years in the Alps (1982-1996) and it was ALWAYS 4 bucks a gallon for Italians, Germans and Austrians!! Nothing really new, eh?