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  1. #1

    Default 1998 seirra 4.3 to 350 5.7?

    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. #2

    Join Date
    Feb 2008
    Red Wing, Minnesota, United States


    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
    99 K1500 Suburban LT "THE BEAST"
    Hypertech III, K&N, true dual

  3. #3


    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. #4


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

    welcome though!!

    2002 Jeep Wrangler Sport 4x4 (the Yellow Jacket)
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    2004 Sierra crew cab, 2wd, 5.3 V8
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  5. #5

    Join Date
    Feb 2008
    Red Wing, Minnesota, United States


    well the transmission needs the computer and everything would be off

  6. #6


    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.

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 277K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half

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