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Thread: Lm7 to L33 swap

  1. #1

    Default Lm7 to L33 swap

    So I blew up my Lm7 motor in my 03 GMC. I want to get a junkyard non flexfuel L33 5.3 I have been told everything will work with my existing wiring, injectors fuel rail coils intake. Is this swap possible? If the electrical doesn't work can I use all my existing electronics from the Lm7 motor? Any help would be great.

  2. #2
    Jr. Mechanic
    Join Date
    Apr 2013
    Location
    East Central Iowa
    Posts
    88

    Default

    Should be fairly simple. Might want to grab the PCM for the non flex engine because of tuning issues.

  3. #3

    Default

    thanks zippstripp. I called chevy today and they were nice enough to help me out and they claim that it should work the PCM should actively adapt. But, I have read somewhere that the 04 and up 5.3 fuel rails do not have a vacuum modulator or a return line back to the fuel tank, although the fuel rail working pressure is the same. I know the injectors are slightly larger on the L33 motors so I was hoping to use those. could I use my existing fuel rail with the new injectors? does anyone know about this? I have already ordered the motor. 55k no front accessories and a 3 year warranty. it only set me back $1400.

  4. #4
    Jr. Mechanic
    Join Date
    Apr 2013
    Location
    East Central Iowa
    Posts
    88

    Default

    Not sure actually. Would bepend on if they were physically larger or just a larger flow rate.

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