The Stovebolt Site Forums The Shop Area General Truck Talk Gas Mileage with a 235

I have a newly rebuilt 235 6 cyl , 3 speed on the column, with a 410 rear end in my 1949 Chevy 3600. What kind of gas mileage should I be getting? Thanks

What kind of driving?

What average speed, and how much start/stop/shifting?

10-16 mpg is a non-educated guess

I have 800 miles on my rebuilt 235, with SM420, and 6:17 rear end.
Most of my driving has been stop and go, sometimes hauling 4-6k in town, top speed of 50.
The truck is a LoadMaster 4400 stake bed, with dual rear wheels, and weighs about 6000lbs.
When we rebuilt the motor we went to standard crank bearing inserts, aluminum pistons, and stock style cam.
I have been tracking my fuel economy for the last two tanks, and so far I am averaging 6.5mpg.

13-14 MPG for my '48. That includes an empirical 20% correction of the odometer reading because of the non-stock rear end and tires. Mine is a 261, though, but I don't think that makes a bunch of difference.

The low gears is what makes the difference. It takes a lot of gas to push that thing 50 mph with 6.17 gears.

Glad to see you're an honest man Curt. When I hear claims of 20
plus mpg with a stovebolt, I have to laugh.
I've put 15k on my truck now and kept a log of all the mileage.
The average is 14-15mpg. The stock 216 engine had complete
rebuild by a major engine shop that is a large marine engine
rebuilder. Original stock engine had about 55k on it. The
mileage dropped off by about 1 to 2 mpg after the rebuild.
Can't explain that other than it was bored .030" over. I was
getting 15+ before it was rebuilt but pushing a lot of oil.
Oh...SM420 with a 4.10 HO52 rear.
dg

I have a '37 with a '57 235 and 355 rear gears. I expected better than 14 but then remembered how hard I push her. I'm currently outfitting her with a 700R so it will be interesting to see how that changes things.

Maybe burning all that oil contributed to the total "fuel" delivery.
Or more likely, you liked the sound of that fresh engine so much you couldn't keep your foot out of it.
Have you checked the fuel mileage after the new rebuild was fully broken in?
Carl

You can shake your head and laugh if you want. I drove back and forth 30 mile round trip in the 47 3/4 ton. It had the gear swap in tech tips, and a 235. i got 19 mpg. I did keep my foot out of it.

"When I hear claims of 20 plus mpg with a stovebolt, I have to laugh." Denny
"You can shake your head and laugh if you want. . . . i got 19 mpg" Bart

Bart,

There are a couple Tech Tips on gear swaps, resulting in different rear-ends/ratios.

What is your rear-end ratio?
What was your average speed?
How did you recalibrate your odometer/speedometer?

Denny's incredulity (regarding 20mpg) is most likely directed to a stock 47-55 stovebolt - referring to a 4.10 rear end.

Somewhere just short of 10K this week on the new engine Carl,
should be broke in by now. last thousand miles-nine fillups
averaged out to 12.08 mpg. And yes I am rather heavy on the
right foot and spend a lot of time in traffic.

Seeing is believing Bart. Figure it over a thousand miles then
give us an honest report.

dg

Straight 2 lane highway driving 50/55 I got 17mpg.

I believe you. What rear end ratio?

Going 50-55 mph highway driving in my 1954 3106 with 3.55 rear ratio and 31.5" tires might get 20mpg. I have often gotten 18mpg highway driving 55-60 mph (on fairly level Interstate Highways).

Stock 235 power train, 3:90 screw with 225/75/15 tires.

I'm on the low end of the spectrum, why, I can't figure out. 3.90 rear, stock 235 (Rochester carb., stock manifolds, Pertronix for sparks) 235/75R-15 tires, three on the tree tranny.
I've tracked every fill up the last year, mostly get mileage in the 11's with an occasional 12. This is with roughly 2/3's flat highway, 1/3 around town driving. I'm going 170-180 miles between fill ups.

Do you have the correct carburetor base gasket? If the gasket is blocking the power valve vacuum port fuel mileage is greatly effected.

Yepper here, correct gasket, but it's a W-1 now anyway!
My 216 runs like a finely tuned sewing machine, no
complaints whatsoever about it's performance. She gets a
tune/up going over every time I change the oil. Valve check
or adjust, carb adjusted, points and plugs checked or
adjusted, she's timed to the ball and vacuum advance is
functional. Starts first turn over, idles down to 450rpm
nice and smooth and still running fine and smooth at 3000rpm
plus if need be to pass on the highway. I've posted video of
her running up to 65 with my 4.10 gear and still had
throttle left.
Just poor mileage, after first couple of years
rebuilding Rochester 'B's then settling in with the old
reliable throwback W-1. Fuel economy never varied, never
better than 15mpg and usually averaging about 13mpg.
Could be the 3/4-ton weight combined with a heavy right
foot. Never had it on a sustained 50mph highway run where
I burned thru a couple tanks of petrol. Might try that this
summer just to see what max mileage is possible with this
combination.
We did drive my buddies '52, 3100 with a freshly rebuilt
stock 216 down to KC a few years back. Engine was broke in
over the summer before we left on the trip. We ran 55 all
the way, cept for some driving round town in KC.
About 1,000 mile weekend and I averaged the fuel mileage at
the end of the trup. Just a hair over 15mpg. Seems pretty
consistent to me for that model vehicle in its relatively
stock configuration.
dg

12/23/2011 15.62mpg. $3.38
1/7/2012 15.78mpg. $3.43
11/23/2012. 14.85mpg. $3.56
1/3/2013. 16.11mpg. $3.07
1/10/2013. 16mpg. $3.03
1/23/13. 14.34mpg $2.97
2/1/13. 16.11mpg $3.13
2/15/2013. 16.25mpg $3.47
3/1/2013. 16.04mpg $3.79
3/8/2013. 16.6mpg. $3.77
3/27/2013. 16.61mpg $3.72
4/10/2013. 16.07mpg $3.67
4/15/2013. 17.75mpg. $3.62
4/19/2013. 16.10mpg $3.59
4/28/2013. 17.65mpg $3.49
5/3/2013. 18.73mpg $3.42
5/4/2013 14.69mpg $4.19
5/5/2013. 17.64mpg
5/5/2013. 17.05mpg
5/9/2013. 15.79mpg $3.40
10/15/2013. 16.12mpg $3.39
10/23/2013. 16.62mpg $3.33
11/26/2013. 16.34mpg $3.31
11/22/2013. 16.75mpg $3.27
12/5/2013. 15.22mpg $3.21
12/13/2013. 14.48mpg. $3.21
12/20/2013. 14.92mpg. $3.21
12/20/2013. 16.81mpg $3.41
12/20/2013. 13.40mpg $3.89
12/20/2013. 15.29mpg $3.43
12/21/2013. 16.34mpg $3.99
12/21/2013. 13.89mpg $3.65
12/27/2013. 11.69mpg $3.65
12/27/2013. 15.69mpg $3.79
12/27/2013. 13.09mpg $3.61
12/27/2013. 15.91mpg.
1/1/2014. 13.49mpg $3.21
1/8/2014. 15.89mpg $3.21
1/16/2014. 15.96mpg $3.18
1/23/2014. 16.11mpg $3.19
2/1/2014. 15.89mpg. $3.24
2/6/2014. 16.04mpg $3.23
2/15/2014. 15.55mpg. $3.28
2/20/2014. 11.75mpg $3.23
3/2/2014. 16.21mpg $3.48
3/13/2014. 15.71mpg $3.48
3/21/2014 16.70mpg $3.47
4/3/2014 16.26mpg $3.47
4/10/2014 16.73mpg $3.57
4/28/2014 15.50mpg $3.65
5/10/2014 16.25mpg $3.68
12/23/2014 14.5mpg $2.47
1/9/2015 15.46mpg $2.37
1/21/2015. 14.44mpg $2.15
1/30/2015. 15.23mpg $2.15
3/14/2015. 15.62mpg $2.89
4/10/2015. 15.27mpg $2.73

I drove my '51 1/2 ton Chevy from AZ to the reunion in Kansas City last September. Round trip mileage and mileage while at the reunion was 2500 miles over 8 days. Some low mountain driving on the western end of the trip (continental divide on Highway 60 in western New Mexico is 7800 ft elevation). On the open road I kept the speed about 55 mph. My mileage on the entire trip was 15.7 mpg. I should add that my truck is stock except for the Coker radials (6.00x16), which should result in somewhat better mileage than bias tires. Also, I am running a Carter YF on the stock 216 instead of the Rochester.

There was a recent thread about comfort in an AD cab and I can report that I did just great (except for that big ol' Texas grasshopper that careened off my driver's side mirror and nailed me on the side of my neck).

Kent

I think how heavy your foot is, city or highway and wind, play a big part on millage.
Kent, you seemed to have a great time at the Reunion last fall and Denny brought it up also.
Think you guys will be ready for a fall KC trip this year?

Don

Don,
I do plan on coming this year and encourage others to do the same. The show has a lot of pickups, panels etc. and Chevys seemed to predominate. I plan on bringing my COE but will trailer it instead of driving it the whole way. It is a very pretty park right next to the Missouri River, the people are nice and it is great to meet other Stovebolters and put a face with a name.

I was happy with my mileage because it seemed I had a crossing headwind both ways. No way to properly account for my headwind without instruments.

Kent

Great Kent!
hopefully John and Peggy will make it this year and you will be in the running for the long distance again.

To stay on topic, pulling a COE on a trailer, will not get you very good MPG. Thats a big wind catcher.

Don

'46 1/2 ton, '54 235 rebuilt in 1986, 3:55 rear, 16 x 7.00 tires.

On the road when I drive to South Carolina from Atlanta I get about 17 mpg running at 55 on the back roads. Around town who knows - 14mpg maybe?

I know the OP asked for 235 but my tired 49 216 in a 3100 is still mostly stock so I'll add it to the discussion.

49 mostly stock 216, 3 on the tree, single Rochester w/oil bath AC, single 2" exhaust w/round muffler and working heat flap, rebuilt head (at stock spec), stone stock bottom end, 4:11 gears, 225-75R-16's on stock wheels, avgs 12.5 mpg on mostly 40-45 mph runs. Gets a little over 13 mpg if I keep the foot out of it and avoid stop & go traffic.

Will be changing to a hopped up 235 soon.

Those of you who have been around for a while probably are
aware that I like to see documented proof when we talk about
certain facts pertaining things like this.
Sooooo.......since they're dang near giving away gas now a
days, i.e., $1.29/gal., I thought I burn up a tank on a
somewhat controlled open road mpg test.
It was a nice sunny clear cold day today and about 11:00 this
morning with my tank topped off at Casey's and the GPS
plugged into the lighter, I headed out from Sandwich, IL
headed for the big river. Got to Savanna, IL some time after
lunch, touched goal and turned straight around and headed back
to North Central Illinois. I stopped in Dixon to drain my
tank and topped off the tank in Old Blue for the trip back
home. When I pulled into Sandwich I topped the tank off again
at Casey's where I made the first fill up this morning.
About 5 hours total in the saddle, never had it over 2400 rpm,
mostly shifting at about two grand, no jack rabbit starts, and
kept her right around 50 mph according to the GPS for most all
of the trip, 'cept for going thru a few dozen small towns cuz
I was taking taking country roads. 154 miles total, burned up
11.74 gallons. Comes out to 13.12 mpg. Probably could have
gotten 14 mpg had I been at 50 on the interstate for
154 miles without any stops.
Then there are the temps in the teens for the day.
1.Heavy air=more drag on an already barn door profile.
2.Weaker gasoline blends in the winter=lower vapor pressure
fuel yielding less power,
3.Tires at 25psi, sweetie face even commented that they looked
low when I was pulling
into the garage this evening.
4.Also warmed her up this morning for about 15 minutes before
leaving.
5.Still have the 15w50 Rotella-T in the engine.
6.To achieve a stoichiometric mixture cold dense air needs
more fuel.

Not related to fuel economy, but to a previous thread on
comfort. Never felt cramped or uncomfortable the whole day
and I only stopped for a break once in Dixon.

Denny Graham
Sandwich, IL