The Stovebolt Site Forums The Shop Area General Truck Talk 10 mpg?

My new van...52 1/2 ton...235...3.55 rear
The motor is very strong...
I'm only getting 10 mpg on the highway at 55 to 65.
I'm going to rebuild the carb.
I'm also going to do a compression test.

What do you guys get?

Don't know, my speedo/odometer is inop,LOL,
Scott

I average around 14, if I keep the ol' size 14 out of it.

I get 13 MPG around town (40 MPH or less) with my 261, SM420 tranny and 4.10 rear end. The odometer has been calibrated. I'm happy with that.

Id guess 14 on average in my '53 with the original 216 and 3.55 gears.

I don't drive any of my jalopies enough to figure gas mileage. However when my father used GMCs as work trucks, we figured 15 miles per gallon. This was with 4.57 rears and 7.50x17 tires. They came with 228's but my father would buy 248 short blocks rather than overhaul the 228's and there was a noticeable change in fuel economy with 20 more cubes. We were gasoline distributors and gas was only 20 cents a gallon, but that 20 cents would buy a hamburger.

In my '55 1st Suburban, with a GMC 270, SM420 and 3.08 gears in the rear, got almost 18 on a recent highway trip running 60 and 70 mph.

Tires are 235/70-15s and it cruises nicely at 70. I was surprised to do that well, I expected more like 16.

The last couple weeks I've driven my '50 Chev 500+ miles and averaged 20 mpg. Its a 216 w/3 speed and 4:11 rear end gears. I realize that a car will slide thru the air some better than a truck but still a close comparison.

10 MPG at 55 MPh. You should be getting at least 20 MPG with that set up.Have that carb checked out. I am running a built 350 with a 700R4 tranny and 3:90 rearend.And getting 20 MPG all day long,city and highway driving.At 10 MPG you gotta be running a way too rich.

I don't think its reasonable to expect a stock 235 with original running gear to compare to what can be done with EFI and an OD tranny. Better than 10 yes, 20? That's a little optimistic.

Don Stocker stated..The last couple weeks I've driven my '50 Chev 500+ miles and averaged 20 mpg. Its a 216 w/3 speed and 4:11 rear end gears. I realize that a car will slide thru the air some better than a truck but still a close comparison.

with 4:11 GEARING, that is really something but if you say it is true............then..

I once got 18 mpg on the trip to the ATHS National Show in Baltimore a few years ago on a 55 mph trip with a stock 235 and stock 3.90 rear end.

20 mpg with a 4.11 rear end and a 216 sounds rear nice.

I am now getting about 15 mpg with a dual-carb, dual-exhaust 261 and a 3.55 rear end. This was on a 230 mile trip from Macungie PA at 60-65 mph with a calibrated speedometer and a very heavy passing-foot.

I get about 19 out of my 350.


11 on the highway and 8 in town, that's 19...

I could drive my 52 to work for 2 months on a tank of gas..

......

Joker I wasn't doubting Don's word, but responding to the later post saying thekid1950 should be getting 20 with his pickup.

It might be possible to get 20 mpg out of one of these old pickups with a stock motor and drivetrain, but I don't believe its realistic to expect it as a daily experience.

Change the rear gears and/or add a overdrive, and update both the ignition and the carb and I bet its still tough to do.

I get 16-mpg in my One Ton. In town, around town, and loaded or empty. I'm in fourth my 20 mph, 15 mph unloaded, as my truck has the 5.14. I would imagine that on the highway going a steady 45-mph, I would do better. But, that never happens, and I accelerate slowly, though all 4, every time. The truck runs 35 miles a day, so it gets to warm right up. Its as good as any real truck I've ever driven in town.

I was amazed by the numbers myself. I averaged it out over 4 days going back and forth to St Paul MN for a car show. Mostly 2 lane driving, 45-50 mph and just taken it easy enjoying the ride. I also have a '47 F**d tudor that was along for the trips and it averaged 11. Its got a stock flathead and tuned properly. Bottom line in my book is the 216 is all its cracked up to being and then some.
Don

Why worry??

dg

And Dale, you should have your speedo checked. I know I only get 15, and proud of it, on my 350 with about the same gearing.

Oldsub,,, your statement..joker I wasn't doubting Don's word, but responding to the later post saying thekid1950 should be getting 20 with his pickup.

I never meant to say you were, maybe it was me...lol

you gotta make sure your tank is full when you figure the mileage and full when you feel it up at the end..20 miles to a gal in any old truck is a lot...........regardless of gearing..
but it is his story so I am sure he is sticking to it..lol

my rod will get a good 20 on the hi-way driving at 70 plus, but it also has 2:73 gears..

I would expect about 15, my 250 sets about that. Its hard to compare a V8 to a six due to the torque curves and low rpm horsepower. It takes a lot of tuning to get a carburetor to work at very low rpm (overdrive)and still pull the truck.

Joe

This one has been flogged hard. Let us know what a van is, willya?

10 miles is not far, but for a step van with the wrong gearing, it could be...

i get 12 with a 235 with dual carbs and 15" tires and 2.73 rear end this around town. ron

Its a 1/2 ton Chevy Suburban

I also have a 51 Chevy 3/4 ton
235, 4 barrel, duals, 3.4 rear, T5...
I get 16.5 over last 10,000 miles

Oh. Heavier than a pickup, but I'd still want more than 15 mpg on a straight, flat highway at a legal, steady cruise. Especially with that 3.55 ratio.

First the compression test, then an ignition tune-up. After that look at the carb. That would be my plan.

Of course, an inspection of tire condition and pressure would precede any of that. What rubber are you running, by the way? OE 16" tires would be a definite negative in looking for economy.

I'm getting 14 MPG with a '53 235 and 3.90 gears

I get about 18 in my 49 3600 when I keep it below 50 with the stock rear axle, 4 speed and 216. same with my 3100 up to about 55 with the stock 3 speed, 216, and rear end. It sounds like a carb issue or to much lead in the accelerator issue.

i have dual carbs on my 235 and 2.73 rearend and when one of the carbs was inoperative i got 19. i was not aware that it wasn't working. as i said above usually around 12. will check again soon, just got it back from the shop. ron