VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 Typical MPG? - 1926/1928 1 Ton Truck

I am finishing up the restoration on my jalopy 1-ton truck (1926 Chassis, 1928 engine/trans, chopped 1923 Coach body made into a cab) and have put ~100 miles on it over the last month or so. Overall (with nothing to really compare to) it seems to be running well, pulling the plugs, they look good, no evidence of burned oil or running too rich or too lean. It cruises nicely at ~33 MPH, I've had it up to ~42 MPH, this truck has 6.00x20 tires and the original 5.43 rear end so these speeds match up with what I would expect.

My question is what kind of MPG should i expect? I seem to be getting in the neighborhood of 8 - 10 MPG in combined driving, is that a little low or about right? I was expecting to get closer to ~12 MPG.

Considering time, evaporation, number of cold starts, axle ratio etc I woold say yoy will be lucky to get 10 MPG.

I would be surprised if that drivetrain could produce 12 mpg especially if you are driving at speeds above 35. The engine is turning at relatively high rpms at those road speeds.

Remember that an engine is really just an air pump (expect you put combustible air into it). Even at light loads the engine pulls a certain amount of air at a given engine speed. The carburetor mixes a set ratio of fuel into that air flow volume. So higher engine speeds require more air which means more fuel regardless of load. And when you have to open the throttle more to maintain that higher speed if takes more air and fuel.

I also suggest that more miles will give you a more realistic number. So drive it and enjoy!!

Thanks Gene and Rusty, that makes me feel better! I've seen some with 28 Chevy cars and Model A Fords claiming they get anywhere from 15 - 20 MPG (which is probably with an overdrive unit and a tail wind) but nothing on 28 Chevy 1-tons or Model AA 1-tons for that matter.

I also get from 8-10 mpg with my '27 one ton truck, Lurch, with a '28 engine and a four speed transmission. I run him 20-25 mph on city streets only. I'm running 6.50x20 tires on the rear and 5.00x20 on the front.

BTW, according to my copy of the Four Cylinder parts book, there were two ring and pinion ratios available for the 1926-1928 one ton trucks: 6:33-1 and 5.42-1. My '27 truck has the 5.42-1.

As an aside, I was told by a VCCA member in Australia that a 1929 LQ (1 1/2 ton truck) rear end has a 4.88-1 rear ratio (8 tooth pinion and 39 tooth ring gear) and these gears are a straight bolt-in affair into the '26-'28 rear ends. He takes his truck up to 50+ mgh!.

BTW, my '28 1/2 ton truck (Justin) gets around 15-18 mpg averaging around 33 mph. I believe the differential ratio in this truck is 4.18 to 1.

Cheers, Dean

Thanks for the info Dean, I wouldn't have guessed that big of a difference between the 1/2 ton and 1 ton when unloaded, good to know. I tried to find one of the '29 4.88 to 1 ring and pinion sets when I was putting my rear end back together but didn't have any luck but I will keep my eyes open.

Just out of curiosity, do you limit your speed to 20-25 MPH because of the engine, brakes or something else? I found mine likes ~25 MPH and then ~33 mph (GPS verified speed)

Hi again,

I should note that the mileage figures for my trucks are with a load. Lurch carries around his wooden cattle cage (sides taken off and laying flat for driving), which is made from oak and is very heavy. Justin carries around a bunch of tools, jacks, and other assorted 'accessories' that I use and also put on display at shows.

Those loads included, Lurch weighs 3100 pounds (1300 pounds on the front axle, 1800 on the rear) and Justin weighs 2400 pounds. I measured Lurch's axle weight at a truck scale to prove that he needed to be put on the trailer backwards (heavier end towards the hitch) for good weight distribution.

As for the speed (or lack thereof), Lurch just seems to be very happy at 20-25 and the temperature goes up a little when I drive over 25. Justin's temperature starts to go up a little over 35 and his sweet spot seems to be around 32.

Besides, I like driving around at the lower speeds. People give me a lot of room on the road (and a lot of thumbs up ;-) ) and the slower speeds help me look further in front of me so that I can react comfortably to any situation that comes up (like someone pulling out of a parking space).

The brakes are in good shape (well adjusted and lots of liner), but I would not trust them to stop me on a dime.

Regarding the '29 ring and pinion gears, I had a set once (still in a pumpkin with the torque tube), but never got around to using it. I let it go with one of my previous truck projects to a friend in the SF Bay Area. I don't know if he ever used it. You might look for a '29 LQ that has a newer chassis and running gear. Maybe the person who did the conversion has the old parts. That's how I found mine.

Cheers, Dean

Puts a big smile on my face Dean picturing you driving these. Didn't realize you drove Lurch with the cattle cage broken down but makes sense after seeing the size of that in person. Be nice if you could drive it with your wooden cows in the back. It would sure lighten people's moods on the road...

The quickest & easiest method of getting some "overdrive",would be to put the LQ 1 1/2 ton truck crown wheel & pinion into the '28 truck torque tube assy.It(the '29) uses the same front,rear and crown wheel carrier bearings,as well as the same splined & pinned tailshaft to pinion shaft coupling sleeve.You could also go for 6.50 X 20 tyres on the rear.Even with this combination,my '28 truck wasn't happy cruising at 35 - 40mph.
After a planned trip to Queensland in 1988,I decided to change the diff ratio altogether,and I went from the '29 ratio of 4.88 : 1,to a ratio of 4.166 : 1 out of a 1924 Dodge tourer.Since that change,it's now happy cruising between 50 - 55mph,drove it to Queensland and back in 1988,a round trip of nearly 3,600 miles,Adelaide twice(1994 & 2004 for the Bay To Birdwood rally),trips around most of NSW,Victoria.Well worth the time and effort,especially the increase in MPG,from a poor 9-10,to between 24 - 25mpg on a trip,and 15 -18mpg around town.And if any one doubts me,ask Verlyn Husman.

Thanks for the note CJP, a couple questions for ya:

1) How difficult was it to find the Dodge Tourer ring and pinion?

2) What all did you need to do in order to install it on your truck?

3) Did you need to do any wheel balancing or anything else besides the ring and pinion change to feel comfortable cruising at 50+ MPH?


My truck actually has a 1926 chassis with rear only brakes so I don't really have any desire to cruise at 50-55 but it would be nice to be able to cruise 35-40.

When I first tore my rear end apart and got everything cleaned up I found that one of the differential bearings had a few of the balls break apart and chewed up the pinion gear pretty good (surprising the ring gear looked pretty good). I looked and looked for a '29 4.88:1 ring and pinion but ended up finding a lightly used 5.43:1 set and decided to go that route.

Just sent you a PM(the flashing red envelope symbol)

Hi TJPlatt,
As the owner of a 1927 Chevrolet truck for many many years and one that has been driven all over the place similar to CJP's truck just be careful what you want in the way of speed.

CJP and Myself have often given our trucks a run to blow out the cobwebs. My truck has the latter 29 diff centre fitted and it will give you a little better speed along with 650 x 20 rear tyres but be sure to adjust the caster angle on the front axle as you will have to retain the 600 x 20 tyres on the front as the larger tyre will not fit on the front.

My truck also runs a 3 port head but unless you change the rocker gear all you get is a better breathing exhaust system. A Tillson carburetor will make a big difference to the standard Carter model.
I was also able to get an overdrive gearbox for my 1927 Chevrolet truck and although it gets along at a greater speed ( I have been clocked at 70 mph on the freeway for a short time) it is really crazy when you consider that you have to be able to stop the truck which is a rather heavy vehicle and with rear wheel brakes not a smart option. The comfortable speed is 45 - 50 mph.
The overdrive with the 29 diff and the 650 X 20 tyres is a bit of a step up and would probably work better with the 600 x 20 size.
As for typical MPG the faster you go the faster the fuel is used.

regards
twin4

Thanks for the info twin4.

To your point about stopping with just the rear brakes, I hear ya. A setup that would allow me to cruise around at 35 - 40 at low-ish RPM is really all I'd be interested in.

Regarding the carburetor, my truck had a Tillotson JR3 on it with a 7/8" venturi, and while it seemed to run OK, the carb was really worn and even after rebuilding, it leaked and spewed gas all over the place. I ended up buying a new Marvel-Schebler TSX style carb for ~$50, replaced the venturi (to a 13/16") and modified the linkages to work with my truck's setup. After making the switch, the engine runs much smother (particularly at idle) and starts right up.

I took the truck out the other day for a 40 mile drive on some pretty hilly gravel roads averaging around 30 MPH and got a tad over 9 MPG (with 10% Ethanol Fuel) which sounds decent with the 5.43 to 1 ring and pinion and the speed I was going based on the previous comments. CPJ is planning to give me a ring sometime this weekend to tell me about how he went about swapping his ring and pinion with the '24 Dodge set. The '29 R&P sets seem to be pretty scarce these days.

-Tyler