mpg?

my mom always bitches about me getting a muscle car cuz of the gas milage. so what do u think a 1970 cutlass with a rebuilt 350 rocket with a intake and exhaust would get in the mpg?

12-18 mpg.

It also depends on the tuning, too.
The can run well, but still waste gas if the carb is too rich or the timing is retarded.
Learn how to tune it and how to play with the jetting, timing and advance curve for maximum mileage.

City driving really sucks down the gas for these cars, especially when its stop and go. But highway driving is quite efficient.

Another important thing is rear end. If you get a 4.10 or 4.11 it'll really suck on the highway. On the other hand, a 3.07 will get you better highway mpg. At the cost of acceleration.

Another important thing is rear end. If you get a 4.10 or 4.11 it'll really suck on the highway. On the other hand, a 3.07 will get you better highway mpg. At the cost of acceleration.

Exactly, I have a 1969 Cutlass that had a 350 rebuilt with a 750 double pumper holly and mild cam and headers with 4.11 rear end. Wow that thing sucked the gas like a big block. I'm talking 6 - 8 mpg on a good day.

It depends on the compression ratio too. Higher compression engines get better mileage, but require higher octane. I had a 70 El Camino with a low compression 350 and a stock cam. With headers and a quadrajet I got 13mpg.

It depends on the compression ratio too. Higher compression engines get better mileage, but require higher octane. I had a 70 El Camino with a low compression 350 and a stock cam. With headers and a quadrajet I got 13mpg. were u drivin normal or were u goin light on the gas and tryin to see how high u could get the mpg.

Another important thing is rear end. If you get a 4.10 or 4.11 it'll really suck on the highway. On the other hand, a 3.07 will get you better highway mpg. At the cost of acceleration. would a 4.11 give u better city driving mpg.

No way. The drive shaft would spin 4.11 times for every 1 time that the tires spin. So the engine is working just as hard. So it would build RPM's quicker, using more gas. The whole point of higher gears is to "let's say" use the same amount of power from the engine to spin the tires less.

thats what i thought. why do they make 4.11's and 4.10's?

They make them for people who want their cars to be quick. Street racers, quarter mile machine and what not.

i know how gears work and why people have them but my question was why do they have 4.10's AND 4.11's if there is only a .01 difference.

I guess it really comes down to what you want. A muscle car or good gas milage. The two don't really go hand in hand anymore :2cents: :shakehead

With gas prices being like they are most people would rather have lower gears.

i know how gears work and why people have them but my question was why do they have 4.10's AND 4.11's if there is only a .01 difference.

4.10 AND 4.11 would not be available for the same rear axle unit. Only one or the other depending on the make and model of the axle in question.

With gas prices being like they are most people would rather have lower gears.

Lower gears have a higher number and would give you worse gas mileage.
Lower gears = higher number. Higher gears = lower number.

Lower gears have a higher number and would give you worse gas mileage.
Lower gears = higher number. Higher gears = lower number.

So what you are trying to say is that when you have something like 4.10 you get good gas mileage and when you have 3.23 or something like that you get bad gas mileage. Do you mean that with lower gears you can reach higher speeds and with higher gears you get lower speeds?

With lower gears you can reach high speeds quickly, but you'll have a lower top end.

With higher gears you won't reach high speeds that quick, but you'll have a broad top end.

In the end, higher gears will get you better fuel economy since you won't be revving so high when you're cruising down the highway.

Usually "mpg" isn't something you mention in the same conversation as muscle cars. It's kind of like taboo in the muscle community. If you wanna drive a car like this, there are strings attached. And if you complain about the fuel mileage it gets, what the hell are you doing driving it then? That's the way I see it. If you like your dog, you give it food and take care of it. If you like your V8 you give it gasoline and enough to keep it running. Same thing.

i dont have a muscle car. and higher gears give u better acceleration and bad top end and bad gas milage and lower gears give u worse acceleration good top end and better gas milage.

That is completely incorrect.

so right now i have 3.27's on my car and when i get 4.10's im gonna get better gas milage?

I'm sorry Bleeddodge but I totally agree with neatofrito. A higher rear gear with shorten every gear. With 4.10's the rear tire spins 1 time for every time the driveshaft spins 4.10 times. That means the driveshaft would spin more with 4.10's to reach the same speed as something like 3.27's. Having higher gears is a mechanical advantage used to deliver the power of the engine in a shorter span. I'm sorry to say you have it backwards. Lower gears strech out that span with 3.27's you could reach a higher speed, have better gas mileage but your car's acceleration wouldn't be as good as with 4.10's.

Mines69Olds is 100% correct. Your best gas milage would be a numerically lower gear like 3.08 or 2.73.

Yup, therein lies the rub... Due to myth and superstition, shadetree mechanics, and all the other buzzing in your ears, the definitions of "higher" and "lower" have gotten lost in the shuffle.
A "lower" ratio (key word here) indicates the "driven" gear will turn a LOWER number of turns based on the number of turns by the "drive" gear. A "4.10" is a good example of a "low" street gear. A "higher" ratio will take fewer turns of the "drive" gear to make one turn on the "driven" gear. In this case, the "drive" gear is the pinion and the "driven" gear is the ring. "High" gears are sometimes called "taller" or "highway" gears. A "3.08" is a common "highway" gear for GM cars.
A "higher numerical" ratio is a "lower" ratio. We didn't really use this terminology until the '80s, though it's been around as long as mathematics. it CAN be confusing...
FWIW

Ok Ok... So nobody was really wrong we were just not on the same page. Sorry Bleeddodge you were right. Thanks MrPbody for helping put everything into perspective. I appriciate the help and learning a new thing or 2.
Matt

i was thinkin the same thing.