1998 seirra 4.3 to 350 5.7?

Discussion in 'GM Powertrain' started by Johnmobilio, Sep 3, 2008.

  1. Johnmobilio

    Johnmobilio New Member

    I have a 98 sierra with 5 speed vortec 4.3 and my friend is geting an 80s(i think) Chevy van with a 350 with 60k. From what I understand the 350 will bolt up to the transmission but will the mounts be the same or just use the 350 ones? Or will I need special ones?

    its carburated so the wiring should be easy?

    I can handle fabing up the exhaust.

  2. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    not sure but i dont think the computer would do such a great job from trying to manage FI V6 to a carb V8, why not just et a vortec they are cheap and easy to find
  3. Johnmobilio

    Johnmobilio New Member

    The computer dont have to do anything it would just kinda hang out I guess?.... the point is that the motor is there for the taking...

    so is this not feasible?

    anyone else know about the mounts?
  4. 04sierracrewcab

    04sierracrewcab Epic Member 5+ Years 1000 Posts

    sorry no help with that ..not really my dept.

    welcome though!! :sign0016:
  5. vncj96

    vncj96 Epic Member 5+ Years 1000 Posts

    well the transmission needs the computer and everything would be off
  6. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    If you want to do that, find a TH700R4 transmission. It's the predecessor to the 4L60E and will bolt up and work happily with that 350 carbed. You WILL need a TV cable hooked up from the transmission to the throttle linkage and it MUST be set right. The TV is NOT a kickdown cable, and if treated as such, WILL cause imminent transmission failure. OK, enough of that. You will also have to swap fuel pumps or find a fuel pressure regulator since the fuel injected pump is putting out sometihng like 60PSI when carbs don't like much more that 10PSI without freaking out. Wait...which vehicle are you dropping this setup into? If you're dropping it into the 98 Sierra, you will have NOTHING, no gauges, no nothing. Everything relies off the computer, and if there's no motor and transmission to get data from, nothing will work.
  7. 95CTburb19

    95CTburb19 Epic Member 5+ Years 1000 Posts

    yeah I don't think that this is going to work out too well.

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