[chevy kevy]

why do 350's use so much gas? I can understand why a big block sucks alot of gas, but why does the 350 use so much( its small and light). If I get on my 350 alot I can just watch the gas gauge go down. I do have a holley 4 barrel and 3:73 gears but
she shure likes to drink the juice.:yes:

 

[Busted Knuckles]

If I get on my 350 alot I can just watch the gas gauge go down:yes:

That's the key. ANY engine will drink a lot of gas when you get on it. On the other hand, a very light foot on a 454 can sip gas very efficiently.

 

[RB69SS396Conv]

There's more to what determines how much gas an engine uses, than just the CID.

It's mostly about whether the engine is efficient in the RPM range that the gearing forces it ro run in.

What's the heads/cam/intake/carb/exhaust/CR of this motor? what kind of car?

 

[chevy kevy]

Doah, after reading my own post I realised I may have answered my own question:clonk:

 

[chevy kevy]

71 chevelle 350 stock, holley 4 barrel, edelbrock performer intake, stock iron heads,headers, pypes 2.5 x-pipe system with race pro mufflers, 12-bolt eaton posi with 3:73 gears. (see sig picture)

There's more to what determines how much gas an engine uses, than just the CID.

It's mostly about whether the engine is efficient in the RPM range that the gearing forces it ro run in.

What's the heads/cam/intake/carb/exhaust/CR of this motor? what kind of car?

 

[Q-ship]

350's are not better or worse at gas mileage than any other engine. If fact 350 will in most cases get better mileage than a 305. Deep gears will do more toward killing MPG. Had a friend that had a SS396 El Camino with 3.08 that got 25 MPG, I know it sounds unbelieveable but I check it myself.....twice.

 

[kettbo]

RAMBO Ben went from 3.31 and 8 mpg to 4.11s and 4 mpg! Think this has more to do with him flooring the gas than the gear swap!

 

[chevy kevy]

Now that I think about it all I ever do is put my foot into it (its so much damn fun) I will have to do an experiment and just drive it normal and see if my mpg goes up.........awwww who the hell am I kidding, I just cant drive her without stomping on it thats what these cars are all about anyways.

 

[ak 67SD]

One thing you say is 'so much gas'...relative to what? have you tested your fuel mileage? it would be good to try a 'lead foot' MPG (over at least a tank or two) and compare to a 'soft foot' MPG....

ak

 

[RB69SS396Conv]

350 stock

Which one? 2- or 4-barrel? What compression? Which pistons are in it? Ever been rebuilt? If so, it's not "stock" any more.

holley 4 barrel

Which one? Square-flange or spreadbore? Vacuum or mech secondaries? What CFM? 4150 style, 4000 series, or Dominator?

stock iron heads

Which ones? (casting numbers ONLY, please) What chamber cc's? What work has been done to them, if any?

"Stock" isn't much of an an answer, unless it goes along with the exact specific description of what it's "stock" for. There's an INCREDIBLE variety of "stock" 350s.

What cam is in it?

What tuning has been done to it? Have you carefully tuned the carb and the timing curve for best results? You can take the same "parts list", and get it to either beat the OE gas mileage specs (if there were any.... I don't recall there being any invented yet in 71) or to drink it like a broken hose, depending on the degree of tune.

Help us out, and maybe we can help you out.

 

[MidLife72]

I get the question all the time...

'isn't that car just killing you on gas'

I always give the same answer. It's no worse than your SUV, I get 15 in town and 21 on the highway.:yes:

 

[chevy kevy]

Well this is actually the 3rd vehicle Ive had that has a 350 in it, and all of them have always used alot of juice. I had a 75 chevy Blazer in 1986 with a similar set up to what is in my chevelle now. of course back then gas was 80 cents a gallon so we didnt care. maybe its a sign of the times that is makeing me realise MPG now. Saturday, I sunk 50 dollars into the tank and it was about gone in less then 2 hours. ( but what a fun couple of hours it was):thumbsup:

One thing you say is 'so much gas'...relative to what? have you tested your fuel mileage? it would be good to try a 'lead foot' MPG (over at least a tank or two) and compare to a 'soft foot' MPG....

ak

 

[RAMBO]

RAMBO Ben went from 3.31 and 8 mpg to 4.11s and 4 mpg! Think this has more to do with him flooring the gas than the gear swap!

Trust me, its the gears... I still drive it the same way, and a tank of gas barely lasts half as long as it did before.

If my car doesn't sell, i'll be looking for another set of 3.07 gears to go back in just so i can afford to drive it again.. Really wishing i hadn't sold them last winter.

 

[kettbo]

what about going back to the 3.31s?

 

[chevy kevy]

I wish I could give more info but I dont have any other then what I told you already, I wish I did know all the specs. It is the original motor to the car so
I just go off of stock specs for 1971. It runs fantastic and I have tuned it
to best of my knowledge. The plugs look good (not to rich or lean) I was told
it had been rebuilt but if thats true or not I dont know. I have had the car for about 4 years now and have never had a problem with it at all, and I have
run it pretty hard too. My top RPM that I have had it at is around 5000 and I dont
think it will do much more then that. I am pretty shure it is not much more then stock internal specs for 1971, flat tappet cam and such. Ill post some pictures of the motor and I have a video cip of me goin down the road so
maybe you can tell the cam by hearing the motor go through the gears. I did advance the timing a tad.

Which one? 2- or 4-barrel? What compression? Which pistons are in it? Ever been rebuilt? If so, it's not "stock" any more.
Which one? Square-flange or spreadbore? Vacuum or mech secondaries? What CFM? 4150 style, 4000 series, or Dominator?
Which ones? (casting numbers ONLY, please) What chamber cc's? What work has been done to them, if any?

"Stock" isn't much of an an answer, unless it goes along with the exact specific description of what it's "stock" for. There's an INCREDIBLE variety of "stock" 350s.

What cam is in it?

What tuning has been done to it? Have you carefully tuned the carb and the timing curve for best results? You can take the same "parts list", and get it to either beat the OE gas mileage specs (if there were any.... I don't recall there being any invented yet in 71) or to drink it like a broken hose, depending on the degree of tune.

Help us out, and maybe we can help you out.

 

[str8tpiperoar]

I wonder the same thing about my truck...its got a stock 307/2 brl and gets like 11mpg.

Something has to be wrong here...either the gears (unsure what they are as rear looks like it was swapped...maybe 373s?), or the carb is junk (dont think it was ever touched since new)

Ideas?

 

[Busted Knuckles]

So "grandpa" drive it all week and reward yourself on the weekend/cruise night. "Delayed Gratification" is what they call it, it's a great discipline tool when you learn how to use it.
Isn't it a lot more fun to watch her remove one article of clothing at a time and tease you, then take your time, than to jump right on and be finished in a couple of minutes..er...seconds??? :yes:
You'll get to drive a lot more often if you take it easy, just like the car :hurray:

 

[scottrock]

I can get an extra 50+ miles out of a tank of gas just by keeping my foot out of it and dropping my commute speed of 80+ down to 70... since the steady rise in gas $$ I stay in the right lane for the 25 miles of interstate I drive back and forth every day and it makes huge difference. :yes:

 

[twotone64]

I wonder the same thing about my truck...its got a stock 307/2 brl and gets like 11mpg.

Something has to be wrong here...either the gears (unsure what they are as rear looks like it was swapped...maybe 373s?), or the carb is junk (dont think it was ever touched since new)

Ideas?

By swapping to a 4 barrel from your 2 barrel will not only give you more over all power, but better responsiveness, and better gas mileage, as long as you stay out of the secondaries. Your primaries of a 4brl are much smaller than a 2 barrel.

My 64 with 3.08 gears, 280h Comp Cam .480" lift flat tappet cam, 2.02 intake valve with 72cc combustion chambers flat top pistons, dual plane intake, holley 600cfm 4100 carb, stock HEI dist from an 80 Camaro, and 700R4 I got 15MPG and the car as it sits can run a 13.9 1/4 mile. the 15mpg was grandpa driving, but driving in the hills of Cali.

 

[Mikeys69]

I have a old set of 2.55's for a 12 bolt...