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"The Highway Hauler"

Discussion in 'Tech Discussion' started by Old-beat-up-77, Feb 4, 2020.

  1. bucket

    bucket Super Moderator Staff Member

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    First Name:
    Andy
    Truck Year:
    '77, '78, '79, '84, '88
    Truck Model:
    K5 thru K30
    Engine Size:
    350-454
    Yep! My combo is a 454/TH400 with 3.73 and 285/75 tires. At interstate speeds it runs anywhere from 2500 to 3000 rpm and it loves every minute of it. Sure it uses a little more fuel, but the engine is always in the sweet spot.
     
  2. 78C10BigTen

    78C10BigTen Full Access Member

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    First Name:
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    Truck Year:
    1978
    Truck Model:
    C10 BIG TEN
    Engine Size:
    350
    Ive got 350/350 and 3.42 with 31x10x15s. Now that i swapped rears im running 265/75r16 tires in back. It always sounds like it needs 1 more gear.
     
  3. TubeTruck

    TubeTruck I like anything fast enough to do something stupid

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    Location:
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    First Name:
    Denis
    Truck Year:
    1978, 1975
    Truck Model:
    Suburban K10, GMC K15
    Engine Size:
    400ci, 350ci
    I'm right there with you. Though I have no idea what I'm pulling for RPM's or how fast I'm going. My speedo doesn't work and I have no tach, lol. If I use my gps it'll tell me how fast I'm going but I don't use it often.
     
  4. 80BrownK10

    80BrownK10 Full Access Member

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    First Name:
    Nate
    Truck Year:
    1980
    Truck Model:
    K10
    Engine Size:
    350
    W
    We're in the same boat. Untill I get the speedometer adapter to screw into the T case I am sorry under by about 30% on speedo. And no Tach as well
     
    Last edited: Feb 7, 2020
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  5. 78C10BigTen

    78C10BigTen Full Access Member

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    Truck Year:
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    Truck Model:
    C10 BIG TEN
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    350
    I put in a tach because the speedo dont work and i never had a th350 before so i wanted to know what i was taching.
     
  6. Old-beat-up-77

    Old-beat-up-77 Junior Member

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    Location:
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    First Name:
    Jeffrey
    Truck Year:
    1977
    Truck Model:
    K10 Pickup
    Engine Size:
    350, 5.7
    Here's a few pics...

    thumbnail (5).jpg

    thumbnail.jpg

    thumbnail (6).jpg
     
    Rusty Nail, 78C10BigTen and TubeTruck like this.
  7. Old-beat-up-77

    Old-beat-up-77 Junior Member

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    First Name:
    Jeffrey
    Truck Year:
    1977
    Truck Model:
    K10 Pickup
    Engine Size:
    350, 5.7
    I also cracked open the SM465... wasn't too pleased with the looks but it rotates without a hitch (surprisingly). I hear these things are bullet proof to a point... Any insight on the validity of that statement.

    thumbnail (2).jpg

    thumbnail (3).jpg

    thumbnail (4).jpg
     
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  8. bucket

    bucket Super Moderator Staff Member

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    Truck Year:
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    Engine Size:
    350-454
    Well they are certainly strong, but I've never shot at one either.

    That trans looks really crusty. Are you planning to just run it and see what happens?
     
    78C10BigTen likes this.
  9. Old-beat-up-77

    Old-beat-up-77 Junior Member

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    First Name:
    Jeffrey
    Truck Year:
    1977
    Truck Model:
    K10 Pickup
    Engine Size:
    350, 5.7

    I'm going to attempt to rebuild it anyway. Even if its old and beat up I'm sure it will still do what is intended and it gives me a backup trans if needed.
     
  10. Catbox

    Catbox Full Access Member

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    Location:
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    First Name:
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    Truck Year:
    1979
    Truck Model:
    C20 Silverado Camper Special
    Engine Size:
    461

    I have read they used them in dump trucks and other large and heavy duty vehicles.
    So for a regular light duty truck like a squarebody, it should be just fine.

    My Camper Special has one that my 17 year old daily drives and he has not broken it yet with the 454 in front of it.
    So I would say they are pretty tough.
     
    Old-beat-up-77 likes this.
  11. Kevin S

    Kevin S Junior Member

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    Joined:
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    Location:
    Japan
    First Name:
    Kevin
    Truck Year:
    1979
    Truck Model:
    GMC C2500 High Sierra, Colonial Yellow
    Engine Size:
    BBC 454, manual SM465
    My '79 C2500 is moving the same way. 454 manual SM465, with 3.21 rear end so already geared pretty high for highway. At 55mph reasonable RPM's in low 2K, at 85+ it nears 3K which is more than I like for distance cruising when doing the Western parts of USA.

    Engine rebuild nearing completion, compression bump to ~9-1, full roller cam/rockers, cam is an Isky 112LSA 205/215 with near .500 valve lift. Mild build, mild cam, Tri-Y headers 2.5 duals. A torque monster build which the power should be strong from ~1600+ Heads were swapped from the peanut ports which die around 3500rpm for ovals which can flow to 5K+, not that I plan to run it at those RPMs. 1500-3000 is where I want usable torque. "Financial friendly" is relative, this build is looking at least 7K all said and done.

    I am strongly considering adding a Ranger Torque splitter which fits between bellhousing and transmission and all slides back 7.5" with shortened driveshaft. Adds a 2nd gear shift in the cab so you can engage the .30 overdrive, each gear can be split (2, 2H, 3, 3H, 4, 4High... reverse, reverse High..) More gear choices to match power to speed, lower revs when cruising which could translate to 17mpg in my dreams. (from the current [email protected])
    https://www.summitracing.com/parts/add-760002m-27/applications/engine-family/chevy-big-block-mark-iv
    That link is for the big-block input shaft size needed for my application. $1600-ish for the part, +install, +welding for your front and rear drive shafts... easily adds up and hard to justify the price just on gas mileage gains alone. I want the gearing torque options for towing. I also plan on keeping this truck essentially forever because I like it. There are cheaper/smarter options out there with more modern equipment.

    Tool for selecting gear ratios:
    http://ctny.audiworld.com/mark/s4/gears/gear_calc.html gear, rpm, speed calculator

    Because the truck aerodynamically is a brick, keep in mind power needs increase with the square of the speed, e.g. if it takes 70hp @55mph to move the truck, @80mph the extra power needed to overcome wind resistance increases rapidly to 120hp+ and more gas. If you can live with lower cruising speeds it helps gas mileage a lot. Things can be done to reduce the coefficient of drag a bit making it smoother, check this thread:
    https://ecomodder.com/forum/showthread.php/practical-guide-pickup-truck-aeromods-32386.html
    pickup truck aero mods.jpg
    I have some clear Lexan and intend to pursue the Wing+Cover option. A partial 60% tonneau cover helps a good bit. Apparently between the cab and the tailgate a rotating mass of air helps support airflow from the rear of the cab over the bed to tailgate. Not quite as smooth as a boat-tail Kammback design, but helpful to smooth the airflow. Add sideskirts, a bit of airdam to keep air out from the underside of the truck, maybe a belly pan... small things add up. The hard part is not going so far to ruin the look of the truck. A certain amount of lipstick on this pig I am willing to test, but it is still designed a pig.
     
  12. TubeTruck

    TubeTruck I like anything fast enough to do something stupid

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    Engine Size:
    400ci, 350ci
    I see. They used the 1/2 gear lube 1/2 water mixture. That way it saves some money lol
     
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  13. Old-beat-up-77

    Old-beat-up-77 Junior Member

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    Truck Year:
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    Truck Model:
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    Engine Size:
    350, 5.7

    Some great info there... thanks!
     
  14. Old-beat-up-77

    Old-beat-up-77 Junior Member

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    New England
    First Name:
    Jeffrey
    Truck Year:
    1977
    Truck Model:
    K10 Pickup
    Engine Size:
    350, 5.7

    It actually came out not too bad. Gears cleaned up pretty good and I just went ahead and bought the Novak Kit. Still have the top cap and case to clean up. Top cap is giving lots of problems but I should have them figured out in a few days. Ill post some shots when I get the chance.
     
  15. Old-beat-up-77

    Old-beat-up-77 Junior Member

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    New England
    First Name:
    Jeffrey
    Truck Year:
    1977
    Truck Model:
    K10 Pickup
    Engine Size:
    350, 5.7
    Anyone have an idea of drive shaft lengths for 350/SM465/NP205 on a 77 K10?
     
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