The Stovebolt Site Forums The Shop Area General Truck Talk 7.8 miles/gallon, sound right?

Yep, that’s what I said, 7.8 miles/gallon! Got about three partial tanks of petrol run through her and it looks like my old 216, four speed, 4.57 geared mama is only gonna give me single digit fuel mileage. I can't remember driving anything that got this bad of fuel mileage since I had my 1941 Cadillac stick shift,flathead V8 49 years ago!
So any of you boys out there got the guts to check your mileage and compare???
Hoggin’ at the pump,
Denny Graham
Sandwich, IL

Denny, my '67 250 4.57 with Rotchester B is a little better at 10 mpg city driving. Getting the carpy gas mileage of a 60's/70's musclecar with none of the fun!

My view would be that driving a crappy muscle car would not even be half the fun of an old bolt! So there!

How fast are you driving? My half ton gets 16-18 with 4.11 gears and a 261. I got about 20-22 with the old 216.

The trick is to keep it perfectly tuned. It isn't easy with a Rochester.

Yep it is fun to drive. I do get a lot of those little grins from the old timers who know what they are lookin at. These AD's touched bout everybody in one way or another that was growin up in the 50's, their dad or granpa. My wife learned to drive down on her grandfathers NC tobbaco farm in his '50, 3104. When I was in high school my boss had one that I remember to this day. He lived a mear three blocks from the Sinclair station that he owned and we used to kid him every night when he was leaving work, about it taking a half hour to get home in that old stovebolt. Just glad I don't have to depend on it for that 70 mile round trip I made every day for 27 years. Ain't retirement wonderfull!!!
Denny Graham
Sandwich,IL

i think someone is hitten on your tank at night with a hose or your leaken

4ontheFloor, don’t take this the wrong way, I’m really not trying to be a smart ***, but that’s simply amazing. You are somehow managing to get as good or better mileage out of 60 year old technology than most of the automobile manufacturers are capable of today. You gotta rank up there with the super tunner dudes that run the big time racing circuits. Has a half dozen Chevy inliners(cars)in the 50's and 60's and never got that bad of fuel milage with them, but never as good as your getting.
I’m sure that a 4.11 would give me a little, mind you a little better mileage, but I can't seem to find one O' those for my 3/4 tonner. And these calculations that I’ve made aren’t cut in stone. I haven’t really done a detailed check yet, just pumped a few gallons in and took a rough guess at how many miles I’d gone before I punched the numbers in. A real scientific study of the mileage is some where down the line but it’s gotta hover somewhere around 10mpg. Speed? Mostly around 40 and 45 mph, occasionally I’ll hit 50.

The Rochester “B”! Ya must not have read any of the thread, about the rather extensive work that I’ve be doing with the Rochester “B” carburetors all summer. Pretty straight forward carburetion, once ALL of the pre-drilled passages are clear and sealed up with new lead plugs, the ball checks properly placed and a power piston operating freely and properly biased, floats leak checked, balanced and properly adjusted, main jet checked for any signs of erosion, (checked with plug gauges and on comparator for form), there taint much else you can do with it but adjust the NEW idle mixture adjustment. That be a steady 22in.Hg. and an idle speed of 500rpm.
How solid is the engine you ask? Fresh valve job, 130lbs across the board (dry). Tune comes next? Totally rebuilt distributor with all new parts, timed ball to pointer, valves adjusted hot to .007” and .014” and the lift checked with dial indicator to check for cam wear. And I think that’s all there is to it.
I’d sure appreciate any advice you could offer to improve the tune of this old 216. I'm open to any suggestions.

Naw, the old gals kept in the barn all night long, taint nobody snitchin gas unless it’s my Big old wife.

Denny Graham
Sandwich, IL

I had a boss once who said a man will lie about 3 things-his salary, his sex life, & his gas mileage. I got 16 mpg consistently from old black truck, 230/3spd/3.73 gears & never over 60 mph. Yes, a rockyB, but I had it apart maybe half a dozen times before it ran OK. If you tried to run 70 w/everyone else, it went down to about 12-14mpg. 7.8mpg sounds real low to me. My 79 one ton 4x4 gets about 7, it weighs about 5000lbs & has 400/auto/4.10 axles.

My 53 half ton only gets about 10-11 mpg with 4.11. I am hoping to improve that when I install the 292, t-5, and 3.07 or 3.22. Don

hey denny, when can i drop my truck by so you can do a valve adjustment and go through the distributor???

man i gotta figure out how to retire!

This may sound pretty duncy on my part but I have always used my ears to get the best gas mileage. I listen to the vacuum hiss and try to keep it as quiet as possible. For those moments when I can't hear the hiss, I watch my steering column mounted "Motor-Minder" vacuum gauge. Yeah!

get rid of that 4;57 rearend.Gop with a 3:08 or ?

When ya factor in the 3.73 gear things look a lot rosier. Figuring a 29” or 30” tire you were probably turning somewhere around 2500 to 2600rpm, but you were covering a lot more miles than I would.
I was coming back from jury duty this morning in my ’97 Sierra in 5th gear I was running 55mph and she was just barely over 1,200 rpm. That will give me bout 18-20mpg on the highway. That got me to thinking what that would look like I ran it in 4th (1:1) and had a 4.56 gear in it.

Stick it in the cargo hold p.j. and ride on back with my ”Big old wife” tonight, she’s in Phoenix for the day. We’ll have ya on the road back home after breakfast!

Ya know little buddy, I don’t have an inside vacuum gauge but I’d bet it’s kind O’ hard to keep it in the green when your doing 45 with a 4.57 gear.

Come on Dale, you been round here three times longer than I have. If ya know where to get a 3.08 (no way) or a 3.90 (next to imposable) or a 4.11 (real elusive) for a ’50, 3604 somewhere in the Chicago area or even with in a couple of hundred miles of here, then ya got the best kept secret. Mind you now, I don't want to change out the original axle housing.
Denny Graham
Sandwich, IL

Hey there Denny: Those are pretty grim gas mileage numbers and I'm sure a lot of that is due to that 4:57 fanny in there.

I got one thought (that's about my daily limit now) as I read this thread. Timing on the mark is what the book says, but common practice is to give it as much advance as she'll take without pinging. Also, check your vacuum advance, when you rev the engine does it move? More advance = more mileage. Other than that, what brand of gas do you use? (I'll buy a few shares of their stock)

My '59 3800 with a 235, a stock 4-speed and a 4.56 gear got around 12 MPG, so unless you've done something out of the ordinary, your mileage is pretty far away from normal. I had 18" tires on the original split rims.
Jerry

That does seem like terrible mileage. My '89 K3500 with a 454 and 4.11 gears does better than that most of the time. But with a heavily loaded trailer it sometimes does worse.

My GMC Suburban with a 270, sm420 and 3.08 gears seems to do more like 14 mpg. I would not expect to get 20 or more, but you sure should be able to get better than 10 mpg...

Denny my all orgional stock 216 low oil press babbit pounder only gets around 10mpg. How-some-ever, Iv'e got 850x16 recaps on the back and the speedo reads 50 when I'm realy going 60.

I may be an anomaly. When I've measured the gas milage I was driving the truck mostly at a steady 45-50 mph and had skinny radial tires on it. I also spent a lot of time tuning the carb and ignition, and I got rid of the restrictive air cleaner that was on it and made sure the one I had was high flow. I've leaned out the mixture quite a bit so it only has the fuel it needs to run well, no more. The main jet is smaller, the idle screw is just slightly lean of best vacuum, the ignition is advanced quite a bit, and the exhaust has a modern high flow muffler. I've gotten as low as 14 mpg with the 261 but that was hauling a load of fire wood on the freeway. I tend to let the engine rev pretty high before I shift. Lugging an engine with a Rochester B does not contribute to good fuel economy.

Its not really that hard to get good gas milage with an old engine. Today's engines are restricted by low combustion chamber temperatures and restrictive exhaust elements. With an old engine you can get away with high compression, lean mixture. If you can keep the vacuum on the engine up under acceleration, you keep the power valve shut and that saves you a lot of fuel.

Thanks for the response guys, that’s kind of what I was out here trolling for. Just looking for what the general consciences was. Although it is kind of all over the place maybe if enough respondents call in we can get some real numbers as to what to expect.
Like I said earlier, I need to gather up more statistics before I can do an accurate mileage calculation on mine. A few partial tanks of fuel taint really enough to get an accurate number, more of a rough estimate than any thing else. What I need now is to build enough confidence to drive it more than 20miles from home. Or maybe enough dough in my pocket to have it towed home if she gives up the ghost on me!!!!

To a limit Waldo, advance to a limit! She should be running at about 95% efficiency with the timing set at the factory spec. Got good gas, Marathon, been running it for years in all five cars and never had a problem. Mentioned earlier, distributor has been completely restored, used old vacuum advance but leak checked it and found it good and yes, it does advance when you advance the throttle. Scroll through these and let me know whether the distributor looks good enough to put back into service. http://rides.webshots.com/photo/2646130180098611668kmCppj

4ontheFloor, sorry I have to simply address ya by your handle, but I’ve been a member for about a year I know most of the other regulars, rather other old timers, by their first names but I’ve never seen your name mentioned. Thanks four the tune-up tips, I’m suure the radial tires are another factor that is adding to your fantastic mileage. In ’74 I bought a new Triumph TR-6 with Michelin radial tires, it was the first car I owned with radials. One of the first things I noticed about them was how far it would roll when I popped it out of gear. Much farther than the bias plies I had always run, told me something about the rolling friction of the radial tire. I wouldn’t conceder the 6.6:1 or 6.7:1 high compression though. So if I under stand you correctly, you made or found leaner main jets for your “B” carb, that right? With out a EGT gauge how do you know your not running to lean??
I don’t know how much less restrictive I can make the AC, the stock spark arrestor is almost like not having any air cleaner on it at all.
My shift points are 5mph, 15mph, 30mph and I wish I could shift to 5th gear at 45mph.
I have some doubt as to the advantage of advancing the timing beyond the factory spec at the low RPM that this old engine is turning most of the time. If we were crankin her up to five grand or so I might believe it would be beneficial.
Denny Graham
Sandwich, IL

That's pretty crappy. When my truck was all stock, I was getting 12-14. Now with the O.D., radials, HEI and dual exhaust, I'm getting 17-18. My Rochester carb hasn't changed. YET.

yeah, denny. could you do a better job with some of this stuff? pretty shoddy work if you ask me...and could you take better pictures so i can see what you're doing?

seriously, in my opinion you should write a book. tom brownell's (how to restore your chevrolet pickup) book is a pretty good reference, but it doesn't come close to the level of detail your are achieving.

keep up the good work!

oh, and i didn't make your wife's flight with the truck, so we'll have to reschedule the valve job hope she had a good time in our insufferable heat today!

by the way, i get around 10 m.p.h. with my truck and since i don't drive very many miles in a year,even though i drive the truck everyday, i'm perfectly fine with it. still better than most of the cars that are speeding past me on a daily basis.

SO true, but you make up for it on the downhill...

I see it was 108° out thar, but of course it was dry so said she didn’t feel the heat. Yeah sure, I believe ya! In a pigs ear! Tks, I just like to take a bunch of pics, they’re so cheap with these digital cameras one can afford to document every move. Besides, with a memory as bad as mine is getting I need all the help I can get when it comes time to put it all back together. Stay cool p.j.

Zat like six of one, half dozen of the other Buddy? Or like six blocks up hill with out vacuum reading and six blocks down hill suckin the life out of the gauge.

Denny Graham
Sandwich, IL

114 was the last i heard for the day :/

it is a dry heat (again) but make no mistake about it. it's hot! grilling only takes half the time because by the time the charcoal is ready and the plate the meat is sitting on is ready to go, it's already half cooked. kinda like a microwave bbq!

keep taking pictures!!!

Sure enough,if ya wanna run a 3:08 rear your gonna have to change out the whole rearend.But that sure makes a lot more sense than getting 7.8 MPG.At that rate I would go broke after a couple of weeks of driving.The only reason I am getting 20 MPG in my 55 with 3:90 gears is the 700R4 overdrive tranny. You can tune that engine and drive very slow,but a 4:57 rear just aint gonna get you good mileage.

Somewhere along the line I'll have to address my speedometer issue. Then I'll be in a position to look at my fuel mileage with some degree of accuracy, but this I CAN tell you right now: Auld girl is going maybe twice as far on a gallon as when I first got her to run reliably. The radials (31" tread height) and the 4.10 diff have made a world of difference. Denny, you need to troll the wrecking yards for 8-hole Suburbans and automatic tranny trucks between '67 and '72. That's where your 4.10 will most likely be hiding, and when it has been installed, you'll find yourself happy at 50-60 mph. When I had the original 5.14 ratio I was always in top gear and always winding fast except when the traffic lights were close together. In fact, the ONLY time that truck was happy was when she was loaded to the gunnels. Now I can run all day comfortably, loaded or empty and, while I don't know what the number is, fuel economy - while not great - is acceptable.

I checked out your dizzy re-do. You do nice work! Surgical gloves? We're going to have to start calling you "Denny, the Dizzy Doctor". Keep checking that point gap though, expecially with new points, that rubbing block will seat and change the gap. One suggestion: put the points "right on the money" with the feeler guages, then put your 6-cyl dwell meter on there and note the reading. Then, in the future you can easily check to see if your gap is changed by just checking your dwell meter. I did this about once a week and found that the gap was constantly changing. That's when I decided it was time for a Langdon's mini-HEI.

You must be living a dream, or you better go back to school to figure mileage. I am very satisfied with my 10mpg.

I don't have any idea what kind of mileage I get on my 216 with a 4.57 diff, because the stupid speedo gear in my tranny is shot.

Grandpa claims he'd get as much as 20 out of it, depending upon what he was doing with it and how heavy his foot was. He also says that it averaged around 16-17.

He also says that when the 235 came along they were more expensive to run.

Now, this is from my grandpa, so there's the BS factor to think about.

However, based on its performance thus far, I'm guessing that I get at least 15MPG with my truck, and that's with the carb set a little on the lean side and me not fooling with the advance at all.

7.8 seems a bit low to me.

Good suggestion for a quick check of your point gap Waldo thanks.
Oh, I‘m not that anal, I got my share of dirty nails! I use the gloves when I’m into the cleaning tank, and sometimes I just forget about them after words. I worked with epoxy all day at the last job so I got used to wearing them a lot.
Don’t get carried away with the heading guys, I’ll give ya an honest report after I’ve been through enough fill ups to gather the proper statistics. I started a log on this old gal on the last tank full. I’ve always kept one on all of my vehicles, it’s old habit left over from when I was a flyer.
When I look at the published average mileage in the “Truck Data Book” for Chevrolet salesmen, they were claiming 13-16 mpg on the average. That seems pretty doable and a pretty realistic goal to shoot for. With a better gear in their back end, I’m sure you could bump that up to close to 18-20 mpg.
Denny Graham
Sandwich, IL

Sorry, I stopped putting my name in my signature for a while because nobody got it right anyway. It's Josiah.

I'm willing to admit my mileage could be a heinst worse than what I claim. I haven't verified the accuracy of my odometer. I should probably get a GPS unit.

I don't advance the timing very far, I just played around with it a lot and found that my engine likes it a few degrees advanced. I am also running a rebuilt dual point distributor so I can keep the dwell and timing pretty well controlled.

I am indeed running a leaner jet- I have a 261 with a mongrel "B" carb made up of parts from a 216 carb, a 250 carb, and a 261 carb. I can't remember what jet I used but it wasn't the one from the 261. I arrived on the value by reading the plugs until I got a nice brown color after a long drive. I'm also running the valves a bit on the loose side of spec, which lowers the overlap a bit and acts like a smaller cam.

As far as it running too lean- it isn't. It behaves nicely on long drives, doesn't surge or buck on deceleration, runs 180 all the time, and the valves haven't receded into the heads. It has been burning oil lately, though, I have bad valve guide seals.

I also have plywood for a bed and have an alternator and an electric fan (no mechanical). Don't forget that the 3/4 ton trucks weigh a bit more than the half.

Whatever your mpg is, as long as you are happy with it it doesn't matter. I think it should be at least 10.

I'm getting ready to overhaul the thing and put in a Jimmy 302, though. That should kill my mileage.

64fleetsides boss is right. Whenever anyone tells me about their fantanstic gas mileage I deduct 25% except for you Denny I'll add 25%. Weeds

Give me a few weeks of drivin the old gal and I'll need some deductin' to Weeds!
Thanks for sharing your tips J'. Oh, I'm not at all happy with the mileage as I first figured it. When I factor in all the things that detract from the mileage with this particular model it really isn’t much of a surprise.
Yep, I’m around 4,000lbs curb weight, the rear springs alone total 14 leafs on each side and the frame front and rear axle are heavier. Your skimpy little 1/2 ton is only coming in at around 3300lbs, probably less since you changed tires and rims.
That extra weight will make a difference, my first car was a 1941 Cadillac 4dr sedan with a tired flathead V8 weighing in at a whapping 4600 lbs, I ran it over the truck scales out on old Rt. 66 back in late ’58. That baby got all of 4 mpg. It was a good thing that I worked in a Sinclair station and gas was only 29c a gallon back then. Also the longest trip I would have made back in those days was over to the Drive-In in Lagrange, and that big old back seat sure came in handy on those hot summer nights! Ahhh, to be young and carefree again!
Anyway back to reality, I’m not putting to many miles on it right now so I was a little premature in my guest’a’mate (spelling?). I was kicking the idea around a while back of making some spare jets to experiment with. I did make cad drawings of them, just haven’t made any up yet. I made up idle mixture needles and a power piston to replace the bad ones in a couple of other carbs that I was playing with. I took a reading on my plugs last weekend after a 30 mile run and I really hate to change anything cuz they’re looking good.
It does seem to run a little rough in the mid range at low throttle settings, seems like it might be running a little rich. I was thinking about playing around with the spring bias on the power piston to see if I could smooth out the mid range any. Ya don’t want to mess to much with the bias spring cuz it’s a delicate balance. I can wind my own springs from wire I got from McMaster so I can always put the original back in if it doesn’t work out.
Gotta go make breakfast and lunch for my “big old wife”, talk at ya later!
Denny Graham
Sandwich, IL

When I drove my stock 235, 58, 1/2 ton back in college (87-93, please no comments, I was working my way through school ), I kept track of the mileage. I got around 12 mpg in mostly city driving and 16 mpg on the occasional highway runs home. 16-18 mpg is what my grandfather reported he got on the long drive each year to see his mother in Mollala, Oregon.

Well bumped the timing up 10° and that's about all. Checked the milage on the last fill up and I'm getting her up to 14.18 mgp this time round.
Gettin things dialed in but I'm gonna need that 3.90 before I see 20 mpg.
Denny Graham
Sandwich, IL

Dad bought a '47 Chevy Fleetline sedan in Wahoo, Nebraska back in 1977, and we drove it back to western Colorado, over 700 miles one-way. He also took it on a trip to northern California in the spring of 1978, putting over 3,000 miles on it on that trip alone, all on a bone-stock 216 3-speed w/OD, and got 21 mpg consistently, especially on the Cali trip. He got a little less driving it to Colorado, about 16.5 or so. AND, drove the Interstate darn near the entire way on both trips. Obviously, the truck mileage is going to be a bit different, but not EVERYTHING back in the day got single-digit mileage, such as some would believe.

The key words there Patrick are passenger car, 3.73 rear end, skinny little 4ply rated tires and most importantly w/OD.
I'm pretty happy to see the mileage comming up on the old gal. Some is due to tinkering, some is due to my being more trusting of the fuel tank and topping it off. At first I was sneaking up on the full mark for fear of the neck or upper portion of the tank leaking so my numbers were more like guestamates. Bet ya wish you still had dads Fleetline.
Denny G

I have never checked my mileage,but if i dont stay on the gas pedal the darn gas tank runs over!!!!!!!!!!!! :whistle: :whistle: :whistle:

I’m at a steady 13mpg +/-.5mpg now. I'll be checking the next tank full with the radial tires on her, I wondering if I will see any difference.
Denny G