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292 get best mileage

Discussion in 'The Hokey Ass Message Board' started by simplyMyself, May 6, 2008.

  1. simplyMyself
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    simplyMyself Member

    I am looking to keep my 292 inline Chevy with my 65 pickup, but I would like to try and get better mileage out of it. These are my considerations that are more simple.

    1. 3.50-4.10 rear
    2. 5 speed transmission
    My next consideration is to put in a MPI or TBI system to tune in better mileage. I have the original single barrel that is being rebuilt right now and was wondering if any thought it would be worth just keeping that, but I am leaning towards a MPI system down the road.

    Does anyone have any better ideas?
  2. scottybaccus
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    scottybaccus Member

    The biggest issue is weight. With limited torque, you will have your foot deeper in it to get rolling. On the hiway, you may be fine, but stop & go will kill ya.

    You didn't say what your target is. Even a light weight truck is doing well to get 20 mpg hiway. What have you seen so far?
  3. old dirt tracker
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    old dirt tracker Member

    your fighting a losing battle trying to get mileage from a 292. that said the bigest bang for your buck is a higher gear rear end.
  4. simplyMyself
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    simplyMyself Member

    I am shooting for about 20mpg if I can with my C10. I am leaning closer to 4.10 and hoping to shoot around 1900rpm.

    MPI will be the last thing tackled, with first shot towards the new rear gear. I am thinking of a T5 from a S10.
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  5. scottybaccus
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    scottybaccus Member

    I think you're bringing a knife to a gun fight. If you ever abuse that T5 in such a heavy truck, you'll be on the expensive end of a bad deal.
    Even with EFI, that's not much motor. If you really want good driveability and mileage, think bigger. A 283 with efi and a 700r4 would be a step in the right direction. The best available would probably be to dig up a 4.8 LS1 from a late model truck. You could probably find one with a matching 5 speed that would be better suited than the T5.
  6. 63Biscuit
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    63Biscuit Member

    I wondered how posts it would take before someone tried to convert you to a V8! Keep 'em in a row!

    Have you consider other possibilities? These could be taller rear tires (although it'll hose your speedo) or improved aerodynamics (OK, weird when applied to a truck, but include a slight lowering of the front end, skinnier front tires, or even a subtle chin spoiler). Hell, I remember C10s have HUGE side view mirrors...you could replace them with something off a modern pickup.
  7. belair
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    belair Member
    1. H.A.M.B. Chapel

    A truck is a heavy brick. Scotty is on the money. F.I. and gears would help, but the laws of physics are unrelenting taskmasters.
  8. simplyMyself
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    simplyMyself Member

    I have lived the V8 life all of mine and have chucked a inline once upon a time. This time, the I6 will stay, but I want to do the best I can with it. It is partially taste and heck, if I did what everyone else did, I would be just like everyone else. I have spent my whole life not being like everyone else, with exception to the engines (still yet to get a 327 at some point). I know I could get a newer engine and slide it in with all the EFI ready to go, but now what would the fun be to getting a bit creative.

    Now if anyone has a suggestion that keeps me in my 292, please spread the gospel, but for the V8's, thank you very much for considering the bigger badder, but for once I think I need to keep the 292.
  9. Halfton65
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    Halfton65 Member

    My 292 is getting 10-12 with a Rochester 1 bbl. If you can find a Holley Economaster for the 292 you'll be golden. There was one on my truck for 20+ years(8 of those years sitting)-zero maintenance and it got 16+ mpg.

    I really miss that carb :(
  10. cwatson1953
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    cwatson1953 Member

    i've got a 292 in my '53 chevy sedan. can't tell you much about my mileage cause its yet to see that much of the road.
    but it will be my daily. i've talked to and seen guys running 292s in full bodied/heavy cars that claim they can get 20 on the highway. maybe true, stop and go traffic is different....and a truck may be a different story.

    i know one thing, and this is straight from Tom Langdon's mouth,...that stock 1 bbl ain't enough. you'll get better performance and possibly gas mileage out of a SMALL 4bbl.
    Tom told to me that the 292s fuction way better with a carb(s) as close to 400cfm as possible. he recomended a holley 390, i went with a carter AFB 500.
    that stock 1bbl i THINK is onlt about 200cfm.
    OR a 2x1 set-up.
    i know i'm not gonna get the greatest MPG ever, my 292 has a mild cam, headers, and a single 4 bbl, but i don't think it will be all that bad.
  11. raven
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    raven
    ALLIANCE MEMBER

    Keep the 292.
    The 283 backed up with a 700r4 will still need a steep gear to be efficient.
    The 292 has enough torque since it's a long-stroke motor.
    Go with a 390 cfm four barrel carb and headers to breathe along with a good ignition and you have a good, durable combination.
    Remember, to direct your attention to increased efficiency. That means breathability and accurate, strong spark along with an efficient air/fuel mixture.
    Find out where your modified combination starts to climb up on the cam and set your gearing to run there for most driving applications. Put a 5 speed behind it, too.
    r
  12. FiddyFour
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    FiddyFour Member

    wow
    i hope louver dude sees this post... he's got a 250 six in his 53 chevy and with a 200r4 he was getting close to 26mpg with it... no reason NOT to expect numbers above 20mpg for a 292
  13. cwatson1953
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    cwatson1953 Member

    26! thats badass!
    i gotta scrap this TH350...
  14. 58Fridge100
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    58Fridge100 Member

    I think it's a cool idea.

    I say stick with it--
    http://67-72chevytrucks.com/vboard/showthread.php?t=276823



  15. Old wolf
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    Old wolf Member

    We have some trucks with 292s they will out pull v8s but use lots of fuel mainty due to 456 gears. Our 64 3/4 ton wrecker gets 23 mpg with a 81 250 intergrated head with a 1 bbl rochester and 390 gears with285 75 r 16 tires. I was thinking of putting an intergrated head on a 292 they have a stainless steel plate type gasket between the intake and exhaust that superheats the gas after it leaves the carb.If you polished and cced the combustion chambers i dont think the compression ratio would be a problem.:cool:OlsWolf
  16. wvenfield
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    wvenfield Member

    An efiecient carb, better breathing exhaust, gears and more efficient tranny will likely gain you a little.

    Then the question is, is the cost above worth the gains. Not to piss anyone off, but I don't believe 26.
  17. Gemini EFI
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    Gemini EFI Member

    Agreed! The TBI will make the problem go away on most street engines. If you make a lot of power requiring serious amounts of fuel delivery the problem comes back. My blown and TBI injected truck makes 460 H.P. and does not have the problem. Harry Sternemann's 800 H.P street driven 9 second '38 Chevy does. That's because of the volume of fuel required. My truck weighs 3400 lbs.Holley 4 barrel TBI, Clifford headers, .512 lift, MSD. 12 lbs. boost. 3.55 rear, 700R4,12.70 on street tires. Gets 16 MPG the way I drive it (hard).
    I can guarantee going to a 283 would be a step backwards in torque.
    Gemini EFI

    Attached Files:

  18. BlackCherryImpala
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    BlackCherryImpala Member

    I've always passed on the integrated head 250's even when I have found them at reasonable prices because I've heard guys say they are problematic, cracking and so forth. Have you witnessed any problems? If no, I'll certainly reconsider one when I find one on the cheap. Thanks for the info. I like the mileage your 64 is getting. BlackCherry

  19. Old wolf
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    Old wolf Member

    There are two types of intergrated heads one has a 2 bbl carb and dual pipes. The one we use has a 1 bbl carb and a single 2 3/4 pipe with a 3 bolt flange this type doesent seem to crack like the 2 bbl ones do. Also electronic ignition will help.:cool:OldWolf
  20. fordorford
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    fordorford Member

    The 292 is inherently a gas hog. The 250 will run circles around it, mileage wise. It is a real stump-puller, but it loves gasoline.
  21. oldsman71
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    oldsman71 Member

    higher gears might make better use of the 292 in stock form. I had one in a 65 chevy pu we put 3:08 in it. it ran better than the 3:90 did! good luck. cjc
  22. scottybaccus
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    scottybaccus Member

    fuel economy is simple math. First CIDxRPM/3456 is theoretical volumetric efficiency of 100%. The best street engines are lucky to find 85%. That is just a frame of reference. Now take a 40 year old inline 6 and the awkward intake and exhaust paths they used and you can imagine that they manage maybe 65-70% ve.
    Now take into account that it takes about one half pound of fuel per HP per hour in a gasoline engine. Can't change that, it's just a fact based on the BTU output of gasoline.
    Now consider parrasitic losses. Maybe 10-15% through a good transmission and rear gear, more if it's unusually deep for pulling. Then add in the wind resistance of a 6' wide brick that stands 6' high and catches air in the wheel wells, under the chin, on the tailgate, mirrors and even the rear bumper.
    All this rolls up to 2 factors. How fast do you drive and how quickly to you accelerate to get there? Say you can achieve 26 mpg at 1850 rpm, that may be at 35 mph or 65 mph, depending on all of these parasites. Now, do you achieve 60 mph in 3 seconds or 13? It takes each vehicle a given HP to accelerate in a certain time frame and then another given HP to maintain that speed. A 2007 vette can pull near 30 mpg at 70 due to the right final drive ratios and tremendous aerodynamics. Put that exact powertrain in a '62 Chevy truck and I seriously doubt you see half that.
    I love inline motors. I just don't think you will see good mileage with such a stacked deck. Anyone claiming 26 mpg, I doubt they are in metro freeway conditions or sustained 70 mph.
    imho
  23. dutchtreat
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    dutchtreat Member

    Here is my 2 cents on the subject.
    Start with a the later model T-5 trans and use one of the TBI intake setups that Chev put on the 305 Truck engines on a Clifford or Offy 4 barrel intake with the adapter to take the TBI unit. Then go with a set of headers and 2.5" exhaust-Clifford made a dual exhaust header setup. If you go single exhaust go start at 2.5" and open it up to 3"
    There is a place in Arizona that does TBI systems and they can make it work for you. This should get you 20MPG if you keep your foot out of it on the road. I built a 1969 Ford 1 ton van and with a rebuilt 302 (I rebuit it) got 18MPG Highway (city was 13 to 14mpg) with a C-4 (that means no over drive) and a Holley 4 barrel setup with the RV power valve.
    A 292 with it's larger stroke will get better mileage than a 250 as TQ is what gets you going and if you use a Vac. gauge to drive off city driving will be good too.
    Good Luck
    Dutch
  24. simplyMyself
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    simplyMyself Member

    There are some seriously great responses from the group. I know I am looking for something that could quite a reach, but considering the issue with the MPI, That is one area that will need to be reconsidered completely.:eek:

    It appears that at least a 4 hole carb is likely the next spot to look at and from what it looks like, a 390-400cfm. Possibly a TBI if I want to screw with electronics that much. :rolleyes:

    Gearing and a 5-speed will be the next place to review.:cool:

    [Next question - Edelbrock or Holley?]:confused:
  25. willowbilly3
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    willowbilly3 Member

    All the 292s I was ever around were thirsty critters, it'll never see 20 mpg unless you can coast off the continental divide with a strong tailwind. If you want an economical (chevy) six then get a 250. It has respectable power and is much more efficient, or better yet put a 300 Ford in it.
  26. 58Fridge100
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    58Fridge100 Member

    I don't realistically think that there is any secret to the difference between a 250 and a 292.
    For one thing, the 250 was far more likely to be found in a much lighter vehicle straight from the General.

    Another thing to consider is, of course- is the low static CR (with a cam that matches) you are working with, and the anemic single bbl carburetor. This motor can't be very efficient in stock form, and has to possess a really short diesel-like powerband...
    Being asked to pull around a 4 to 5,000 lb vehicle with a long legged three speed manual transmission-- of course it will be very thirsty. It's being asked to perform outside of it's tiny little sweet spot for the majority of it's operating period.

    The great thing about the 292 is that it's a stroker, so it HAS to be an ideal straight six to pull that truck around. It just needs a larger powerband, and like everyone else says- some extra gears w/overdrive.

    I'm not so sure that headers/ large diameter exhaust is something that's required. In fact, with a respectable "RV" type cam, a little smaller exhaust will help the efficiency of the motor through improved exhaust scavenging..
  27. willowbilly3
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    willowbilly3 Member

    My comparison is based on similiar model 1/2 ton pickups of the day and there was a big difference in milage between identically equipped, basic 4 speed, 2wd longbed trucks in stock form. The 292 has a well earned rep as a guzzler.
  28. simplyMyself
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    simplyMyself Member

    Let me ask this question... was the 292's that you drove stock setup or were they altered with work done to try and to make them more fuel efficient? Or, did these 292's you drove just written off as gas guzzlers and nothing more than that? What were their carb, trans, rear setup?

    I ask these questions because I have heard from people that have their vehicles dialed in and are getting an average around 18 mpg. This isn't going to be driven hard, I can put in a 327 and get what I need from that if I wanted to do that, or better yet, a late model chevy engine, though I would much prefer a 327 if I wanted to do that. I am looking for those tricks that may help me push me closer to the edge of efficiency. The first will be to do without the 1-bbl and get towards a 4-bbl that can get a better tune-ability. Most of this can be done without breaking the bank, but if someone had experience that showed that putting the funds in the right spot, I would consider it, again depending on what I see there.

    I thank you for your input, willybill.

    I appreciate all the feedback I have received thus far, guys.:cool:
  29. cwatson1953
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    cwatson1953 Member


    and on a side note....when i changed out my intake and exhaust for the headers and AFB... i have NO problems with it "lagging" from a stop....it's a toquey ass motor...it will move...AND with the headers and 4bbl....it sounds GREAT! of course...the lack of finished exhuast mufflers help that too:D...actually a little too loud at rev...but really good at idle:D

    good luck and keep us posted.
  30. nexxussian
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    nexxussian
    ALLIANCE MEMBER

    FWIW I have always heard the 292 was thirstier than the 250 (disproportionately).

    Having said that, a better intake and exhaust has to help. Even if it's a hommade split exhaust w/ dual pipes that should be better. But if you can find a set of SMALL tube headers, that could help too.

    I have wanted to try the Offy Dual Port 360 on a straight 6 for a while (w/ heat for the primary charge).

    I would reccomend an Edelbrock (500) at this point (for what you are trying to do).

    Gears (trans or rear) are a great idea, be carefull not to get the total drive ratio too tall, or you'll be lugging the engine and in power enrichment all the time. A slightly taller set of tires would help (radials, and if you change the gear or trans you are gonna have to recal the speedo anyway) and run them as high a pressure as you can stand (within the manufacturers inflation limits). Synthetic grease in the wheel bearings helps (a little, but it's cheap and easy). Make sure your brakes are not dragging.

    Aero mods as previously recommended, lower it (if it's not already).

    Then there is the inside of the engine. More compression would help. With that drastic a change (intake and exhaust, especilaly if you up the compression) you will probably want a different grind on the cam.

    A set of the port lumps might help help as well but you should probably ask that on the Inliners forum (search 'Lump Port Heads').

    There is a book by Leo Santucci that's worth having if you plan on doing much to the engine.

    Keep us posted.

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