Register now to get rid of these ads!

Technical 59 truck mpg"s

Discussion in 'The Hokey Ass Message Board' started by jeffd1988, May 24, 2016.

Thread Status:
Not open for further replies.
  1. jeffd1988
    Joined: Apr 12, 2016
    Posts: 536

    jeffd1988

    Hello once again. I made a post earlyer but got deleted and not sure why i changed the topic from mpg"s to what it is now. I have a 3/4 ton 59 apache with a list of all the new stuff i put.

    Crate 350 long block 260hp
    New tko600 .64od
    Ram air air filter
    Pertronix 3
    Electric fan
    1406 edelbrock carburetor
    Timing 34 total
    Full time vacume
    =10 mpg highway

    This set up has 460 miles on it. Do i have to wait a couple thousand miles before i get true mpgs? This is my first ever brand new motor to deal with so i really would like to know what you guys are getting and how? What am i doing wrong? This is driving at 65 highway about 2k rpm 2100 rpm new tires that are 31 3/4" and rear end i believe is a 4.56.
     
  2. 1959apache
    Joined: Nov 22, 2009
    Posts: 2,628

    1959apache
    Member

    Rear end is the first thing I would be looking at. What fuel pressure regulator are you running and what is the PSI of your fuel pump (electric or on the block)? Four things you need to look at, your cam, your fuel pressure, timing, rear end gear ratio. All of these will play a role.

    I run a 350, roughly 280ish+ hp (most of the same stuff you have on yours), 700R4 Trans (overdrive) that is built for 1300hp with a 3.90 gear ratio rear end, I have the same mileage as yours, and I do about 2100 RPM at about 75ish.

    I can lay a decent line of rubber, do donuts to my hearts content, and give some punks in rice burners a run for their money. Ultimately, I don't care about MPG because I like the noise it makes when I mash the pedal to the floor.
     
    jeffd1988 likes this.
  3. 1959apache
    Joined: Nov 22, 2009
    Posts: 2,628

    1959apache
    Member

    Also, it was probably deleted because of someone getting upset that you aren't building it "traditionally" with stock parts or an era correct vehicle. This website was much better a few years ago when the rules weren't so stringent and people came together here to bitch about rat rods and street rods together, instead of segregating one another. Ahhh, the good old days.
     
    jeffd1988 likes this.
  4. Truck64
    Joined: Oct 18, 2015
    Posts: 3,684

    Truck64
    Member
    from Ioway

    It is important to know what mileage or economy is possible or typical even if in the single digits, if only to get an idea when a tune up is necessary or something is seriously wrong. Wasted fuel washes out rings and dilutes crankcase oil, fouls plugs and performance suffers, etc. Best performance is generally best MPG so what's not to like? For my part it's always been a matter of range that hurts, not so much the $$.
     
    Register now to get rid of these ads!

  5. 1959apache
    Joined: Nov 22, 2009
    Posts: 2,628

    1959apache
    Member

    Totally agree.... and I get about 10MPG if I can keep my foot out of it..... if I were worried about gas mileage I would drive a Prius... my reservation would be that I would prefer to keep my soul and man card intact a while longer...
     
  6. Truck64
    Joined: Oct 18, 2015
    Posts: 3,684

    Truck64
    Member
    from Ioway

    You could put a gun to my head and I couldn't point out a Prius or tell you what they look like, sorry lol!!!
     
  7. jeffd1988
    Joined: Apr 12, 2016
    Posts: 536

    jeffd1988

    I have a fuel pump on the block and it gives out about 3 1/2 psi. And i ask about mpg because i know alot of you carburetors are getting 16+ i was getting that in the old 283 that popped on me. And that was with no od tranny taching 3200 rpm at 65. I want to be able to take this on 3 hour road trips to reno, fresno ect..
     
  8. brokenspoke
    Joined: Jul 26, 2005
    Posts: 2,874

    brokenspoke
    Member

    The gearing of your rear end is killing your mileage...3.55 will help a bunch...I get 18 mpg..
     
    jeffd1988 likes this.
  9. Gearing and a better tune. I pulled 20mpg in my 54 Chevy with a similar setup. Final drive in mine was a 3.73
     
  10. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 7,774

    theHIGHLANDER
    Member

    Since you have OD and tall tires the gear ratio may only be slightly suspect, especially given the RPM at the speed you recorded. So that brings up another point, the "best" RPM/Speed combination. As counterintuitive as this may seem, try to run a bit faster, get the engine into it's own happy spot. In my very low tech (no tech really) way you can sort of tell where an engine wants to be by the drone. As you gently increase speed there's a set of sounds the engine will make that lets you know where it wants to be. Sounds silly and childish, I know that, but it's there. Speed it up about 200 RPM or more and I wouldn't be surprised to hear it got better. It's possible that it's simply loaded just a bit much at 2100, and there's a weight factor involved. As I recall a 3/4 ton wasn't a light package to begin with, even in early trucks like yours. Good luck...
     
    Last edited: May 24, 2016
    jeffd1988, gas pumper and milwscruffy like this.
  11. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,947

    gas pumper
    Member

    Her's a fact. The engine is most efficient at it's torque peak. If you are only at 2000 rpm at cruising speed and the torque peak is at 3000, you are killing the efficiency. You need to gear cruising speed to be in the range of the torque peak. Most of us that get good mileage just stumble upon it but you could plan for it. I have a C-30 with 350 and it had a TH400 and 4.10 gear, it got 10 mpg highway. Now It has an OD stick and gets 17.5 highway, same engine and rear, just got the engine slowed down to about 2300 at 70 mph. it was over 3000. too low rpm is as bad as too high at cruise.
     
    Last edited: May 24, 2016
    jeffd1988 and Tim like this.
  12. theHIGHLANDER
    Joined: Jun 3, 2005
    Posts: 7,774

    theHIGHLANDER
    Member

    Rt on 'pumper, torque peak. Since it's a crate I'd bet a cup of coffee there's some dyno "sales pitch" somewhere in the vast 'net wasteland. Armed with that you could taylor your gearing or driving habits to the peak TQ, or at least really close.
     
    gas pumper likes this.
  13. blowby
    Joined: Dec 27, 2012
    Posts: 5,974

    blowby
    Member
    from Nicasio Ca

    Maybe. Depends how the engine clearances etc. were set. Old time rough cylinder wall finish had a lot of friction until the rings bedded in. Even my new at the time 1996 Chevy pickup gained 2-3 mpg once it loosened up, and it took way over 500 miles.
     
    jeffd1988 likes this.
  14. We are building hot rods right?

    When did we start worry about gas millage? HRP
     
  15. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,770

    2OLD2FAST
    Member
    from illinois

    You show 34* total adv. That's w/o the vacuum adv. , right ?? W/o vacuum adv. you could try 36-38*, just listen for "ping". W/vacuum you should be 46-50*.
    dave
     
  16. blowby
    Joined: Dec 27, 2012
    Posts: 5,974

    blowby
    Member
    from Nicasio Ca

    I have heard guys run more advance with ethanol, and some run less. Also to be considered is his advance curve, since running down the highway at 2K won't be at full mechanical advance.
     
  17. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 1,770

    2OLD2FAST
    Member
    from illinois

    Valid point !!
    dave
     
  18. Ryan
    Joined: Jan 2, 1995
    Posts: 18,718

    Ryan
    ADMINISTRATOR
    from Austin, TX
    Staff Member

    Hey fellas... This is a traditional HOT ROD and custom forum. Please stay on topic.
     
    302GMC likes this.
Thread Status:
Not open for further replies.

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2020 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.