[Ethan1]

Hi,
My '72 Chevelle 400sbc .030 over and 435hp. At least that is what I was told when buying the car. Now, I know muscle cars weren't supposed to get good gas mileage, but my car still shouldn't be drinking gas like it is now. I have to newly rebuilt qjet on it and runs great. When the car is running, the needle in the gas gauge just keeps on moving. This happens when in "park" or "drive". It doesn't really matter. I was going to change the rear end out of it, but I don't have the garage to do it in. What can I do to get alittle better gas mileage?

Thanks,
Ethan

 

[SWHEATON]

Need more info like what base & total timing are you running,do you use a vac adv on the dist,whats carb setup like prim jets & meter rods,what gear are you running,what stall in converter if running auto trans?

But your typical non od trans 400cid street muscle cars get anywhere from 5-11 maybe 12mpg on avg of that gives you any indication of where you should be. The hotter setup would be in the 5-8mpg and milder in the 9-12mpg area with poss a little better mph on open road /not in traffic cruising at a reasoable speed like 60mph.

BTW,what exactly is your mpg when you checked it? You should not go by watching the fuel gauge,that will get you nowhere esp since the last 1/4 tank almost always goes the quickest due to the fuel tanks shape having a little less fuel in last 1/4 tank as when compaier to the 1st and 2nd 1/4 tanks comming from the full mark.

You should not worry about mpg with a 30-40yr old 400 street muscle car because mpg was never a good trate of those cars/motors. The only way to get good mpg with them is to run o/d trans and to build the motor with mpg in mind too and maybe installing TPI or other EFI setup would help even more. But with no od trans of some sort you will not normally in most cases get good mpg (20-25mpg)with a street 400 muscle car unless maybe your runing 256-273 gear and have your carb dialed in on the hairy edge of too lean along with a good timing curve.

scott

 

[Ethan1]

Scott,
It was probably pointless of me to of typed this topic. I'm only 19, but I do understand these cars weren't made for good mpg like the cars are today. I love my car very much and was just wondering if there were any other ways to get ALITTLE better gas mileage. I can't answer what base and total timing is, since I don't have a timing light nor do I know how to use it. I think I have vacuum advance on the distributor. Is it just a little vacuum pod coming off the dist. that connect to the carb? I'm sorry, I'm not sure. I'm not sure about the metering rods either. I'm not sure about the stall converter either, sorry. The last time I heard about what my car gets mpg wise, was 4.5-6 mpg.

Can you tell me more about an overdrive trans? Mine right now is a TH-350. I need help with tuning the rebuilt Qjet, too. I'll probably buy the timing light here real soon anyways.

Sorry that I don't know more, but I am new at working around engines. My father did it all the time and can only remember little things.

Thanks,
Ethan

 

[Stalkingbear]

My 2 cents.... the gas we have now - doctored with Ethanol - has a much lower BTU potential that the old GOOD gas...

Less power, more fuel burned to move down the road.

 

[Ethan1]

Mike,
How do I change from pumped gas to Ethanol?

Ethan

 

[rustbucket79]

Your best friend for mileage is an airfuel ratio meter. An innovate LM 2 would likely pay for itself in time by allowing you to tune the carb for peak efficiency.

 

[Guest]

He, He!!

Onna my B-i-L's had a '70's G/P w/ a 455 in it! The wife had to barrow it for like a week or two and she said when she was going across town on Broadway, she could actually watch the gas gauge drop!

The old G/P was a NICE boat tho!

pdq67

Best Car Insurance | Auto Protection Today | FREE Trade-In Quote

 

[Stalkingbear]

You mis-understand, Ethan. Ethanol is not good gas. You have alredy been switched by all the mis-guided people who are convinced that 'corn fuel' is better than 'dino fuel'.
What you are buying is laced with ethanol.... nothing you can do about it.

 

[DOUG G]

Look at any gaspump.... 10% or 15% Ethanol....not a good thing.

 

[Stalkingbear]

I have read that a mixture of Acetone (3 oz.), Xylene (3 oz.) and synthetic motor oil (1 oz.) will really wake up a tank of the bad gas. I have not tried it so I will not speak for what it does or does not do.

I do know a person who had issues with a 327 'vette in a Stude' truck that was running like crap - he added the mix and the truck ran excellent after a few miles. He claims it worked on the truck. He tried it on his wifes' car and it did nothing.

I have had good luck with adding a quart of racing gas to the tank of bad gas... really helped the pinging that I was getting from the (don't laugh...) "high-test" gas that I had bought.

Mike