The Stovebolt Site Forums The Shop Area Engine Shop 235 gas mileage?

What mpg range should a Chevy 6 cyl 235 get?

Depending on alot of stuff ,how good the engine is , how fast you drive,what tires you have,etc,etc.You can expect anywhere from 12 to 16 MPG on my truck 52 3100 with 235 power glide engine all else is stock 3 speed trans,stock rear end and 215/85/16 tires,I get around 14 MPG to 16 MPG.


Pete

54/3100/235, 235/70/15 rear tires and a 2.73 rearend and a t-5 trans. i get 15 around town and 19 cruising and on a long trip i have gotten as high as 24. and average 17-20. BTW i have dual exhaust and dual carbs.

Wow, my old 235's never got anywhere near that good. Must'a had a brake shoe draggin'...LOL

So at 11 mpg with single carb, Patrick's rear end differential, and radial tires - I need to look for problems like carburator, or timing? Cylinder compression was good when purchased.
I do have Vintage Air A/C that was going during my mileage check.

Ron (WE b OLD), what percent overdrive T5 do you have? They range from 18% to around 30% overdriven in fifth gear. 60 mph with your tires, a 2.73 rear, and 30% OD (1.91 final gearing) would only be 1400 rpm and I was wondering if the 235 can handle hills or a headwind with that gear. The 18% ( 2.24 final gearing) would be around 1625 rpm at 60mph which would be closer to a 235's torque band I would think. Do you by chance have a tach to see what the revs are at 60mph? Thanks, Evan

Has standard 1951 3 speed on column.
No overdrive. No tach.
Does fine going up inclines. Don't really have hills in my area.
Cruises well at 60-65.
Carb was bought recently as a rebuilt unit from Bowtiebits.
Ray

Does your 51 still have the original torque tube rear end with 4:10 gears?

I just ordered a 'tiny tach' (google it) for $47 it just uses a wire wrapped around a spark plug wire, it has its own battery that is supposed to last 5 years. The bad part is they claim the battery is not replaceable. But I figure it will get me through the start up of my new engine.

Yes i have a tach. i believe it is 18%. it does well on short duration hills but on a long up hill run i downshift to 4th. at 60 it runs at 1600. hard to read it is under the dash. i had it on the steering column but the guy who put it back together stuck it under the dash. my in town mileage went up 25% when i installed E3 spark plus, the are not cheap $6.00 a piece. i have put the old ones back in to see if that made the difference. i think i have a bent push rod so it will be a while til i can check it. i keep a complete record all that goes in the truck and the MPG is not speculation, or bragging. i have driven the truck to KC 3 times and the mileage is consistent. i drove it last Sunday on a 80 mile trip and filled up before i left and when i got back and it was 19.5 mpg at a 50-60 mph.

Okay. So I have a 216 with the standard 4 speed and 5.14 rear diff. I ride on 265/70R17's (31" tires). What kind of mileage should I be expecting?

probably about 11

May have found where gas mileage has gone -- dripping down the road.
When motor is running there was a fairly steady gas drip from fuel pump.
Have changed to fuel pump and I'll see if that helps MPG.

If the diaphragm failed, it may have leaked into the crankcase and diluted your oil as well.
You can do a smell test, or if its close to time for a change, just change it a little early.

regards,
Leon

Hi All, To those of you w/a 235 who claim are g. tetting 16-20mpg either you need to check the accuracy of you speedometer or tell me what is wrong w/mine because I have a 235 in a half tn 36 that has been rebuilt w/ 308 differential, t5 trans and 17" tires and I get 10.5-11.5 around town and 13.5 on the highway.Also running a rebuilt Rochester carb.the motor purrs like a kitten, Has plenty of power, starts immediatly cold and hot nd ticks over perfectly at idle. So why am I not getting 16-20mpg? Any ideas? cause I would sure like to know since I have tried everything I can think of. (even had it on an emissions detector machine). Thanks...Richard

I can get 18 MPG at 60 MPH with a 261 souped-up a little and a 3.55 rear end and 31.5" diameter tires (my odometer/speedometer is calibrated).

Maybe my rolling box is a little more stream-lined than your rolling box?
Maybe you are quicker off the line?
Maybe you wear out brakes faster than I do?
Maybe this is just another unexplainable mystery of life?

Let's hope we hear from the guy who gets 38 MPG with a 292 - he knows something that none of us knows?

Are they standard 17" or low profile. I found the manual. I got it back in 91. It is from Eagle Research Inc., called caburetor enhancer. No b.s. this realy works. I drove it for quite a few years with it. I'll put it on my new engine too.

And then there was the 200mpg vaporizer carburetor:
http://www.byronwine.com/files/200%20mpg%20%20carb%20.pdf
Of course we can’t forget the Fish:
http://www.rexresearch.com/fishcarb/fish.htm

But in reality, 13-15 mpg is a realistic figure for a 216 or 235 and that‘s all that Chevrolet
claimed back in the day. It’s my opinion that if you’re getting better than that with a stock
AD truck then you can sleep nights knowing that you’re more knowledgeable that all the
GM engineers that worked for Chevrolet back in the day. Maybe we’re just better
educated today.
Can you improve the mileage by changing the gearing, of course you can, but what you
add to one side of the equation you gotta remove from the other. Acceleration and hauling
ability goes right in the dumper. “MORE POWER” Tim- The-Toolman would say. Yep,
more power will compensate for that new gearing, but more power comes at the cost of
fuel economy. Mentioned was aerodynamics, above 50mph that definitely becomes a
factor. But short of cleaning up by removing ornaments and chopping the top 8 inches
there isn’t much you can do to an AD, and you can‘t make an Art Deco into an Advance-
Design.
I picture a dog chasing his tail whenever I hear fuel economics discussed.

I’ve never understood how one can expect 20mpg out of 60 year old technology when it’s
a rare thing even today to find a pickup that will give you that kind of mileage.
Denny Graham
Sandwich, IL

Denny,

Even the folks at "Eagle Research, Inc." tout their Electronic Carburetor Enhancer (in combination with their original Carburetor Enhancer) as allowing an engine to improve MPG by up to 25%. That would get us 15-22 MPG (at the most).

I wonder if the stream-lined style of an A-D panel body would be reducing the turbulence and result in a more economical airstream? (This is not something that I normally think about when I am awake, asleep, or in a mind-altered state).

I get around 15-18 mpg in my 1-Ton. I drive slow, and take off slow.

Did I mention I drive slow? I generally chug around in fourth at 25-30 mph. I almost always start off in first gear to get rolling. I've found that I get the same mileage loaded (2500lbs) or empty, I just accelerate slower when loaded. I also coast to lights, and always try and keep the wheels turning when creeping towards a red light, so I'm not accelerating from a dead stop. Like driving a big rig. On the rare occasion I run on the highway for any distance at 50 mph, my mileage is about 15 ish, or a little lower, depending on how windy it is. Going fast costs money, so I leave early, and take the two-lane scenic route.

I have dual carbs, and headers, but I've never actually put my foot all the way to the floor.

When driven as my friends drive (like maniacs), it gets 10 mpg.

Tim, when I get the panel on the road here, I expect that it'll be so aerodynamic that I'll have to stop every once in a while and siphon the gas out of the tank,so it won't overflow.


I think mileage is personal, and depends more on driving habits than anything else. If you try and keep up with modern traffic when leaving a light, you are going to burn allot more gas, than if you just run up through the gears at fully loaded dump truck speed.

Bebop, put a vacuum gauge on it and do some test driving. I'm going to bet you're only going to have 3-5 inches of vacuum unless you're coasting downhill. You're over-geared, and the carb is running in its "power" range all the time. A T-5 pulling 5th. gear against a 3.08 rear end is the equivalent of about a 2.10:1 gear. Either run the transmission in 4th. gear, or swap to 3.5-something axle ratio. You've got too much of a good thing, especially with those tall tires.
Jerry

When I had my 235 back in the 70's and it was rebuilt, I only could get 15 on a good day. Then I had a 59 1/2 T rear with a 3 speed trans. I put in it. [open rear] When it comes down to it, it's all about how you drive in the end, gas saving triks or not.I don't know about the 200mpg stuff, I'm happy with the 38mpg I got on the hiway with 5th gear. I hope it is as good with this new motor [292]. Only time will tell. Remember in the 60's the Falcon got 30mpg I had one. The Jap's did better during WW2. My 72 toyota celica got 35mpg with the a/c on. Who's kiding who these days. 40 plus is the best now??????