OK so I ahve a 235 with a single barrel and a 3 speed. Its KILLING me on gas. Right now there is raw unburnt fuel spitting out the tailpipe when it is cold. I am not sure how it is while driving, but there has got to be something I can do to improve gas milage. So the question is, what do I do to get better milage.
First get thee over to inliners.org, there are some write ups on how to fix the cold starts. Basically you use the manifold heat to "preheat" your carb and vaporize the fuel/air mixture. Doesn't do much for your HP but does improve cold starts and fuel economy. The second thing you could do is upgrade the carb from the single barrell Rochester (I'm assuming that's what you got) for a Holley/Weber 2 barrell. stovebolt.com sells the carb and the adapter plate for the conversion.
Start by replacing it with a 205/292.... oh you're serious about keeping it? Start by converting it to an electronic ignition. Langdon's has them. Add some form of free-flowing exhaust (headers, Fentons with duals). Make sure your valves are properly adjusted. Make sure your carb is properly adjusted (rebuild?). Running single barrel? Replace with a Holley 390 four barrel. Check timing. How many miles are on the engine? Cam in good shape? (replace if excessively worn) try that. r
It has a petronix ignition already its got stock exhasut manifold with about 3 feet of pipe and a glass pack the motor was rebuilt about 2 years ago, so I assume its good. And I know this is a stupid question, but how do you adjust the timing ( turn the dist), and where should it be?
I still haven't figured out why so many people slam the 235. Anyway, mine runs and sounds great with the engine mostly stock except I ditched the oil bath filter, went 12 volt, and put a set of split tube style headers on it. It's my daily driver. I have not noticed any problems with the mileage. But I average about 5 miles a day
Interesting thread..!! I just wanted to post and ask about the mileage with inline sixes... A friend of mine is interested in buying one, but with gas prices between 6 and 7 dollars a gallon, he wanted to know about how much fuel they use... Can anyone tell me a little about what mileage they make with their 6 bangers... Doesn't really matter what displacement.. All info is welcome here! Thanks! Maurice
"its got stock exhasut manifold with about 3 feet of pipe and a glass pack" Give it the opportunity to breathe. Headers or Fentons or something like that. They like to breathe and this will also increase the 235's performance, if one can use 235 and performance together without laughing hysterically... "And I know this is a stupid question, but how do you adjust the timing ( turn the dist), and where should it be?" This is NOT a stupid question. Look just above the starter for a kidney shaped hole. You will be looking at the front side of the flywheel. Rotate it until you see a 'dot' (or circle) and a triangle. One of those is the timing mark. I think it's the dot. This should be 5 degrees before TDC. That is the factory timing mark. That is what you want to shoot with your timing light. Mark it somehow with some light/bright coloured paint. When I installed an electronic distributor in mine, I set the timing by ear. Loosen hold down bolt for distributor and while the engine is running, rotate it until you hear it stumble, Note where the distributor is (make a mark). Then trotate the distributor the other way until you hear it stumble (make mark). Rotate distributor half way between these two marks. When I installed my rebuild 235, this method worked great. It got around 21 mpg. that is until it started to eat cams (3). Then I got rid of it for a beater 235 (14mpg) until my 250 is ready (next month). r
I estimated a conservative 12 mpg, highway, driving my truck home from the purchase. That's a 250 in a C-10, running rich, with stock exhaust, a bad carb (stock, gummed up and black inside), bad distributor cap, sorry transmission, loaded bed, and leaky tires. The odometer's busted, so it was really our best guess based on mapquest and our fuel tank size, but still.
If it's running right, a 235 should be able to pull 14 or so in town without driving too gingerly. 18-20 on the highway through stock gears. They've been known to pull 25 mpg on he highway with an overdrive. I tried buying a 57 Chevy Bel Air off a guy one time that had 21k original miles on it. It had the 235 with a powerglide. It didn't feel that slow, certainly not like the 54 Bel Air Powerglide I test drove once, and the guy claimed 21-22 on the highway. He was kind of full of shit, though, so your results may vary... I agree with what everyone else is saying. If you open it up a little with better breathing, both your performance and mileage should slightly increase.
I am running a 235 with unknown miles, 3 on the tree, a set of fenton splits with a pair of smittys, and the mentioned 2 bbl with the adapter plate, and was told it has a mini- hei. I am getting about 22-23 on the highway. It sounds good and runs good, although I get a little blue smoke out the exhaust from time to time. Make sure your carb is decent, or get it rebuilt, and hit it with the timing light. Good luck!!!
The long intake runners let the gas fall out of vapor and then not burn efficiently. If they are syncronized and jetted for economy I think two carbs could/should get better mileage on an inline 6 than one or three carbs. Port injection would be the best, I'd look into running two Jaguar sedan SUs since the engines are similar in size. 3.8L = 232"
My '63 SWB with 230 has no mods, but the 5 speed S-10 tranny. Todays tank of gas, i got 17.8 mpg, and that is mostly in town. Cain't bitch about that, bubba.
i wanna say my 235 w/ a fenton and 2x1's is getting almost 20 on the freeway, and when i finish the 700R4 im working on, should easily be able to cruise 75 getting mid 20's or upper 20's
i get about 12-15 mpg street/highway on my 225 slant 6. should get better mileage when i add a super six carb (2 bbl) and dutra duals exhaust manifolds...
That's pretty sad I just got a '05 Dakota with a 3.7 V6 and it says it gets between 16-26 mpg. I figured with the kind of driving I do I average around 20mpg. You would think these guys would be way ahead of the game 50 yrs. later.
Get in there and get your hands dirty. I had a 54 wagon with a 235 when I was 15 and could replace that carb in the dark without a light.(I wasn't smart enought to put an inline filter, just kept swapping carbs for a cleaned one) That has to be one of the simlpest carbs ever. Get in there and fix it. There is nothing wrong with points, just maintainence. To answer your question, my best friend had a 60 belair with a 235\3 speed and it always got over 20.
Well, with the petronix (like I have as well) there are no points.The main prob with my 235 is the carb. It just needs a little adjust now and then. It seems to piss off most people that this motor does so well on gas. Problem is, it's not so fast...yet But I plan on sacrificing some mpg for hp.
I had a 52 chev school bus I'd load to the gills w/flea market junk & get 14 mpg,I lowered the float ,set the timing & it didn't even use oil.Great engine you could have a bad float or else to high,maybe wrong jet? Bob
You didn't mention if this motor is in a car or a truck, although I'd guess it's in a car because of the three speed, or what year it is. The manual trans car usually got a taller gear and a common swap is to put a powerglide car rearend in and get a little less gear, which will also get you some gas milage. Ideally with most engines you want to be turning in the neighborhood of 1800 RPM on the highway for optimum milage, I will find out what you need on a 235 soon enough. They say these engines will do 25 MPG if you run a 3.08 or close gear with an overdrive of some sort. By the late 50's most of your cars were capable of 18-21 MPG, driven conservatively and with no hi-po or power robbing (AC, power steering) options. I had a '60 Pontiac 389/hydro for a driver that got better gas milage than both an '87 Safari (307/200R4) and my current Suburban (about the same weight, 350/700R4). The '60 would do 18-20 highway, both of the others topped out at 17, although the Suburban did it on a trip I did 75 the whole way.
You really want the motor turning more RPM's... since i'm in process of putting the 700R4 behind my 235, and speaking with the guy at buffalos trans adapters, and Langdons, you idealy want to get a 3.73 or 4.11 rear with the OD. anything less and you might not be happy with the end results because the motor will be too low RPM wise for cruising on the freeways, and have not power. One of them has a pick up with a 235 semi built motor with od and getting upper 20's per gallon with a 3.73 rear!!! I am putting a 3.73 in mine, that should be the ticket for good performance and gas milage, i'll post when done about results, hope by next week to be back on the read, and then about a 2200 mile road trip in it, i'll check milage and let you know...
Was getting 22 mpg. in the 250 with a 3:08 gear/350 trans. Put the 4:10 in it and can watch the guage drop (really). Got a 700r4 from Draglinks but won't have it in for a while, too many places to go and not enough time.
My grandpa had some pretty serious Chryslers in his day and even those, in the pre emmissions era made decent mileage. The average daily driver isn't going to have an wild mods or any emmisions equipment, and for most of us no accessories. Its all a matter of keeping your vehicle in proper runnimg condition, and if no one is looking driving like a grandma doesn't hurt either
I got 20 - 21 MPG out of the 235, 3 speed that used to be in my 59 Belair. The engine was completely stock, but I had changed the rear end from 3:55 to 3:36 gears. As far as setting the timing, look right above the starter and you'll find a small hole in the bellhousing, where you can see the front of the flywheel. On the flywheel there should be some kind of a mark, a dot or something, (mine had what looked like a BB pellet embedded in the flywheel). Line this mark up with the pointer that is in the hole, and your engine should be at Top Dead Center. Next, on the distributor (where the vac. advance clamps on) there should be an advance scale and a line scribed into the block. Loosen the vac. advance from the dist. and set the scale to 0 degrees advance, (lined up with the mark scribed on the engine block) and retighten the clamp to the Engine Block (leave it loose to the dist). Next rotate the dist. so that the #1 plug wire is set to fire, (0 degrees advance and timing at Top Dead Center) and retighten the vac. advance clamp to the dist. Basically what you are doing is, indexing the dist to the advance scale on the vac. advance clamp. Now all you need to do is set the timing with the timing scale, (usually about 6 - 8 degrees of advance). After it is indexed, you don't even need a timing light to set the timing, just go off the scale. Concerning the fuel out of the tailpipe, that sounds like a carb. prob. (choke stuck on, leaky float or not set right, or maybe the heat riser is stuck). By the way, 235's are one of the BEST engines ever designed. Not really for performance, but in terms of relaibility and longevity.
Maybe you have a choke problem???Last year driving home from Ill. I got 17.4 at 70 mph in my 59 El Camino. One-one bbl.no problems
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