84’ GMC Jimmy 383 Bad Mama Jama

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  • 7A34C511-EB16-42D3-988F-B6D39A3A42D8.jpeg I purchased my first K5/Jimmy September 2019

    I have been wanting one of these for a very—very long time. When I picked it up it was a running driving unit. It needs some work but nothing out of the realm of my capabilities. Almost all the rubber needs replacing and now so does the engine.

    The first major obstacle was the drive shaft. The drive shaft that came with this truck was torched. The CV had broken and sheared the ball cup off the yoke completely:

    So I had a brand new custom drive shaft made for me featuring all 1350 U-joints by Drivelines North West here in Washington. Great customer service and fantastic guys. Definitely go to them for your driveline needs:

    Life was really good after that:

    Then after taking it on its first ‘maiden voyage’ round trip of just over 80 miles the fans basically quit cooling. (Electric fans).

    So, like any man with tools, I began tearing the heads off the engine. A compression test showed cylinder 8 was full of coolant:

    After inspecting the cylinder walls I am still not 100% they are not cracked in #8 (they weren’t and it was honed out). It appears a ring seized/broke or possibly someone had broken a spark plug end into the cylinder at some point:

    I have the engine dropped off at the local engine machine shop to be inspected

    Ended up being fine and the engine was hot tanked, honed, polished the crank, decked the heads new rings, bearing, and valves were used:



    In the meantime I am able to button up some of the smaller things.

    LMC Door Panels and Manual windows installed:

    Fixed the wing window handles that were flopping around:
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    Painted the radiator support:

    Made a custom headliner since the original was falling down:
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    And as of creating this build thread 10/7/19. That’s where we sit today. Hopefully by the end of October I’ll have a new/freshened up motor and be back on the road before the holidays.


    Motor is back from machine shop:
    Eagle 383-C Crank
    Speed Pro Pistons
    Comp cam 268
    Scorpion roller rockers
    Trick flow aluminum heads
    Edelbrock performer RPM intake
    QFT Slayer 750

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    Engine is in and running. Still needs some kinks worked out.


    Cooling problem was sorted out and narrowed down to the fans. Electric fans out and flex-a-lite went in. Runs at the perfect temp now.


    Pretty sure my trans pan gasket was mashed from sitting on a jack and block of wood with the weight on it. So I’m planning to have that fixed today as well.

    Still has an exhaust leak at the passenger side collector I’ll have to address as well.

    We are getting closer to being back on the road. Hopefully by tomorrow 11/30/19 I can take it for a quick test.


    Still no test drive yet. Fixed the trans pan leak and retorqued the valve body while in there. Burnt my starter up.

    Hood is on. Got the grill letters outlined in Chevy orange.



    It finally has moved under its own power. Time to button up all the small things left to finish and finally enjoy having my dream truck for a while.


    Truck went on it’s first journey out of the garage. Got it all tuned in. Making the small adjustments to get it running right.

    Went with an Edelbrock AVS2 650 carb. Not close to as powerful as the QFT but it gets the job done for now and doesn’t flood my engine.

    Took it about 50 miles yesterday. No problems. Runs great. Nothing but smiles here.

    Well, just as I predicted in the discussion on this build thread..... the 700R4 didnt take long to detonate. Im thinking the TV was stuck or possibly a hair out of adjustment. I did everything I could to get it set and i kept losing gears. Now it has 1-2 but no 3-4. Pulled the pan and its black..... so........

    Im putting an SM465 4 speed in
    pretty dirty but came with everything needed for the swap.

    Cleaning it up and painting it chevy orange to match the motor.
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    looks brand new inside and turns smooth.

    Took out the interior and inspected the floors. To my major surprise this unit is rock solid. No rust. Thats a rarity here folks...

    Rebuilt the clutch pedal assembly while I could and installed it. Only took a couple hours to fannagle it under the dash.....
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    Cleaned up a whole mess of bad wiring and got my tach leads traced down. Next up Im fitting up a new adapter to the SM465 and TC. Then its new gaskets, reassembly and paint. Then I can install the Trans and TC unit and pull out the junk 700r4. This how she sits as of 1-22-2020
  • Year:
    Sierra Classic
    Factory Options:
    383 SBC:

    Eagle Crank
    Forged Speed Pro Pistons
    H-Beam Rods
    Comp Cams 268
    Trick Flow Aluminum Heads
    Scorpion Roller Rockers
    Performer RPM Intake
    Edelbrock AVS2 650cfm
    Monster 700r4
    2500 Stall Converter


    Sm465 4 Speed
    Transfer Case:
    Stock Steering w/
    ORD Stiffener Kit
    Greaseable Shackle Bushings
    Engine Cross Member
    Sway Bar Kit

    4” Suspension Lift
    Rear: 14 Bolt
    Front: 10 Bolt W/ 8 lug conversion
    Gun Metal

Recent Build Reviews

  1. America.Mike
    "Awesome build man!"
    K5Devil likes this.