Even though I do not drive my 37 Chevy p/u much that has a 57 235 I would like to get a little more gas mileage out of it if possible since gas is close to 4 dollars a gallon,I have a T-5 behind it with 3.55 gears and it seems like its only getting about 10 miles to the gallon at its best and the plugs are burning clean. It got better mileage when it had the original trans and rear end and really started to drink gas after the T-5 installation,the rear I put in originally had 2.79 gears which got switched to 3.55s after I noticed the gas consumption issue and I played with the jet and power valve spring and its a little better then right after the trans and rear end swap. My other old cars with small V8s and no overdrive get close to 20 on the highway so as much as I like that old stovebolt six I am seriously thinking about going with a V8,if anyone has any ideas I would like to hear them before I start yanking a motor.
A 235 can pull 20-25 mpg under the right conditions, at least guys have claimed in cars like 49-54 Chevys. 10 MPG, something isn't right. My 1-ton dually gets better than that. Surprisingly a 2-carb intake helps these, or you can go to a YF carb or pretty much anything other than a Rochester B. Take the B and throw it up in the air and shoot at it. Even an adapter to a later Rochester 2bbl will help you some.
I am going to see about a newer YF and go from there,I have a older YF and it looked to have gotten moisture in it and even after a rebuild could not get it right.
I have a 235 in my 54 and get 20mpg. I have a t5 with 376 (out of a 96 S10 Blazer) or so gears. I have a Fenton header and dual carb intake with 2 of the 2 barrel carbs I got from Langdon. I also got the adapters and linkage from him. I run the exhaust through 1 3/4 pipe and Smitty mufflers. Other than that, that is all the changes I have made. I can run down the road at 70 mph comfortably and get that mileage. I did have the carbs synchronized and all by a guy that knows his stuff. Hope this is some help. Later, Dick
I agree on the carb issue. What are you running for a distributor? And what about your timing? I set my 235 with Langdon mini-HEI so that it starts to ping under a load in high gear, then back it down slightly. This way the initial timing is way advanced from the book setting, but the engine runs much better and gets better mileage too.
I have a stock 235 in my 60 wagon with the original 3 speed and the stock rear and I get 18-21 mph so something is amiss in your set up.
Is the speedometer gear right? or are you just guessing the mileage? My son gets pretty good mileage in his 59 pickup with the 235 (around 15), he shifts real early. Has the original rear gears and granny 4 speed.
The speedo is not right but I know how many gallons I put in and can estimate the miles driven and 10 to 12 is all I think its getting,it has the original distributor and the vacumn advance is working. It still has the original Rochester B carb and Fenton headers,I could never find the ball on the flywheel so I have no idea where the timing is as I do it by ear. I was told in 59 the cam was changed for better low end torque so I do have a 60 235 I could drop in and maybe help.
I run 2 Model B's , and have gotten 24 on highway trips. Around town mixed driving 15 is OK. 2.93 rear and 1:1 trans. Will run 75 mph all day and get 20. Howard cam, dual ex, Hei, etc. I'm running I'm pretty sure a 52 main jet in both.
Motor has less then 10,000 on it so its not worn out,the more I think about it the distributor is a reman from Napa and maybe time to let GMC Bubba have one of my extra distributors and do a electronic conversion.
They get decent mileage with points, but it does help if you set the timing. Electronic ignition won't set the timing for you.
16mpg consistently on my 50 pickup Stock rear, granny 4 speed 54 car 235, 216 manifold Carter YF 787s
1959 bel air 4 door, 3 speed od, bellingham to monroe swap meet and back with about 400 pounds of crap in trunk and back seat. 15.5 mpg.
i got a 58 chevy fleetside with a tired 235 with a t-5 combo out of an s-10, triple rochester model b's on a progressive linkage with dual exhaust with the stock 58 rear end. I get between 18-20 mpg on long hauls maybe a bit more. Ill also mention that the motor has a pertronix electornic ignition.
I will try bumping up the timing some more,the flywheel has no timing ball or a place one went in so I have to time by ear.
Is there a reason you went with the higher gear? In the 59 dually I had, I ran a 2:79 highway gear with the 235 and never had a problem getting off the line. That extra few hundred rpm at speed can really suck the fuel Posted using the Full Custom H.A.M.B. App!
those engines were built with torque and long life in mind and economy secondary! with f.i. on them the economy improves.
With the 2.79 gears the gas mileage was worse,I think those motors were designed to spin faster and slowing them down gets them all out of whack. It seemed to get better mileage with the original 4.10 gears. Maybe a more modern YF might help since the newer motors were not spinning so fast,my dad had a 86 Ford van with a carbed 300 and AOD and that barn on wheels would get 21 on the highway.
There are two other things that cause you to have to mash the gas pedal a little harder to go and get terrible fuel mileage with a 235. I can't tell you the number of times I've seen someone with power or fuel consumption issues, that had the valves in their engine way to tight or to loose. Another often overlooked problem when people rebuild the 235 engines, is the rocker arms and the shaft they rotate on. More often than not, these things have been starved for oil and the rocker arms will have worn into the bottom side of the rocker arm shaft and worn through the bottom side of the bushing in the rocker arm itself. If you have any wear at all on the rocker arms, you will get crap fuel mileage. I'm not saying that is what you have wrong, but obviously something is causing a power loss and a fuel appetite.
those engines need a lot of low ratio gearing to get the vehicle going and with a 5 speed trans and a high gear ratio, you're wasting gas just to get rolling.
Two one barrel carbs, synchronized, will give you the best and most even fuel delivery to the end cylinders and therefore should give the best mileage. With one carb, in the middle of that long log intake, some of the gas falls out of atomization before it gets to #1-2 and #5-6 intake ports. Gas won't burn (well) if it isn't in a vapor state. If you have two carbs on a log manifold, spaced with one more or less between #1-2 and #3-4 and one between #3-4 and #5-6 then it should get close to the same mixture on each cylinder. Timing is important too. Retarded, it will burn more gas and run hot. (Too advanced it will burn valves and piston tops...) A tri-y into one balanced header will work better than the typical front three / back three split exhaust too.
I've got a '61 235 in a '37 Chevy coupe. We just got back from a trip to Bowling Green, KY (yeah, I know - a little too early for the HRR). The trip was 750 miles each way, all on Interstates at around 70mph average speed. With the driving around in the area, we drove just a bit over 1800 miles. I got 23mpg. The car's got the original transmission, torque tube and rear axle with a B-W R-10 overdrive welded into the torque tube and 3.73 rear gears. Shifting in & out of OD is manually done with push-pull cables. A few years ago, we took a trip to Rapid City, SD and on into Wyoming. We put on 3700 miles on that trip and got similar gas mileage within a few 10ths of a gallon.
I am going to check the distributor and see if the mechanical advance is working,the distributor is turning so I know the vacumn part is working but the other parts could be froze up.
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