I have 72 cutlass supreme that I am turning into a daily driver. It has a stock 350(except for duel exhaust). I would like to have a little more power but still have a reliable daily driver. How can I do this without affecting gas mileage.

 

Have that quadrajet tuned to run lean and mean and keep your foot out of it. Usually power and economy are diametrically opposed in a carburetor equipped engine. You would need to tune it to the tee, put some taller tires on it to help on fuel economy but then it will seem a little more sluggish on the start, Same for changing rear end gear ratio to a "taller" number (ie from 3.23:1 to 2.73:1 or similar) As far as the reliable part goes, it would be the same for any car; good tires, brakes, cooling system, generally take care of it and keep it tuned up well.

 

How about something as simple as a few minor engine mods and throwing a 200-4R in it. Better first gear, overdrive, plus lockup. That's what I have in mine, bolted right in.

 

You can't have power and gas mileage. The best you can do is keep it tuned up and running well. Of course, you could always buy one of the Edelbrock multi-point EFI set ups. However, they are very pricey.

 

Make this car your toy and build for power. Buy a cheap economy car and use it for a daily driver. win win

 

I like this idea. Keep the motor mild, keep it tuned lean. Overdrive and lockup is going to be the biggest gas saver if you do enough highway driving to make use of it. And depending on the MPG you're going for you might be able to get slightly lower gearing for the rear to put a little more "fun" in it.

What kind of mileage are you hoping for?

 

Olds64 - why can't he a have performance and mileage? I do, my car hauls *** and gets over 20mpg on Mid-grade! Look at some of the new stuff, it runs pretty well and doesn't get bad mileage either.

Why not an Accel throttle body kit instead of that "pricey" Edelbrock system? Full tuneability and it'll lock up the converter etc. Fuel injection, mild mods and the 200-4R, it works well on mine!

My point is there is more than one way to skin a cat.

 

There is more than 1 way

I got a measured 17 mpg on a 455 with a q-jet, and a 3.55 gear in a 66, I just had to keep it under 60 miles per hour.
All I wanted was an overdrive to go with it.
SUPER dependable, and I had less in the whole drivetrain as one of those EFI units cost.
Options abound.

Be carefull about running lean.
Lean on primaries (only a tad), stay rich on the secondries.
My opinion.

 

The best bet is to give it a tune up to stock specs and leave it. I still believe there isn't a way to merge performance and high gas mileage.

 

Yank out the V8 and install a Russian 4-banger like they do in Cuba.

 

That would be good for gas mileage.

 

X2
What were you driving before? If it's a 4 or 6 cylinder and a newer car (2005+) don't expect the same mileage out of a 70's car. They weren't being built for the high mileage comparisons of todays manufacturing for emmisions and economy.

A Cutlass with a 350 is a pretty darn good performer. Is it a high miler? You can't expect a car that has high mileage to be as tight and have as good compression. If you want to minimize the amount of money you're going to throw at the car, Jesse is 100% right. Tune it up. Also like Oldsguy suggested, avoid putting the gas foot down. If you've added dual exhaust, that's one of the first steps to letting the engine breath better. It might not give you a noticeable boost in performance, but he engine will thank you for it.

Change your oil and diff fluid. Make sure the AIR FILTER and pcv valve are clean. Little stuff like that is most often overlooked and makes a big difference.

Of course no one's going to follow the econo rules all the time. If you've got AC and are using it, don't expect impressive mileage. Those old systems can drain 10% or more off your mileage when they're in use.

 

as long as you dont have a lead foot you should be okay, maybe run some seafoam through it and then have it tuned...

 

I have a 69 olds Cutlass supreme which is a daily driver, I noticed that it gets decent gas milage and has awesome power, the only thing that has been changed on it was dual exaust and a Holley street avenger carb. I keep it tuned up and use quality oil and filters. I dont know what gears I have but 75 on the highway takes light pressure on the gas pedal. Power wise if I floor it from a stand still it can light em up, get up and go. I wouldnt see why you would need to change anything. I use to have a 1972 cutlass 4 door 2 barrel. Everything stock and that car was fast and still got stock 350 gas milage. If your not feeling it I bet it just needs a good tune up, if you want to improved gas milage and power you could go with an electronic ignition, which would help the spark and burn all the fuel better, some headers for breathing, and an electric fan and water pump. That would take unecesary drag off the engine and improve preformance and gas milage. Those are my next projects for my 350. Mabey you could try something like that.

 

to get the best gas mileage the engine has to run efficient. the best thing to do would be the 200-4R but there other performance things you can do to improve mileage. i am no expert on it but do know that to make your engine run more efficient sometimes you have to increase power. i had a 72 cutlass with a 350 2bbl single exhaust. i was getting 14 miles per gallon. the engine was in great shape and ran great. i tore it down to give it more power. i went to what equaled to 9.90 compression, a nice cam, 4bbl carb, duel exhaust, had bigger intake valves installed and had the valve pockets opened up a little. i did nothing to the transmission or rear end. when done i got 17 MPG. and the power (by the seat of my pants) was doubled. also the 91 Quad 442 got less MPG than the Quad 442 W-41 and the W-41 would blow the standard 442 away.

 

If you get the carb tuned lean i hope you drive around on flat ground an dont put a load on the engine if it pings thats bad its like a blow torch to the pistons and rings the best bet is tune to factory and use premium gas

 

hmm I have been talking to friends and a few are trying out this hydrogen system that you put under the hood you can buy it as a kit or build it your self and they say it improves mpgs and your engine runs better as wellas cleaner.That is at least what they told me.But then I have one friend that has a 80's diesel chevy with three tanks and he runs it mostly on veg oil.He told me he went to fla from Ny state twice basicly for free.