LS Swapping my '95 Silverado (5.3 LM7)

Discussion in 'LSX + Carb Swaps' started by gothicsera, Aug 11, 2016.

  1. gothicsera

    gothicsera OBS Enthusiast

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    I know there's a couple of threads on here detailing swaps, but I'll make one too. :)

    After a load of consideration I've decided against rebuilding my 350 TBI and I'm going to drop in a 5.3 LM7 instead.

    I swapped an LQ9 into my '80 Camaro last year so it seems only sensible to take this route with the truck too.

    I intend to keep this a fairly stock swap. I'm not really intending to do any tuning on the motor other than a decent cold air intake set up. This is my daily driven truck and also used for hauling my Camaro on a trailer so I don't want to compromise reliability or low RPM torque. Hopefully it will also boost performance and economy over my rather tired 350 TBI.

    I'll be converting to cable throttle to keep things as simple as possible and be looking at getting a reprogrammed ECM/PCM with all the emissions stuff removed along with other changes to make it work well in my truck.

    I'll also be rebuilding the transmission with a 4wd output shaft so I can bolt up my transfer case and keep the 4wd functioning.

    Does anyone know if the VSS in the transfer case is 40 pulses per rev? If so it looks like I'll just need to add a low range switch to my floor shifter.

    Here's the motor and transmission, from a 2002/2003 Tahoe. There's no ECM/PCM and the throttle is DBW.

    Is the stock TBI fuel pump actually a high pressure pump regulated down? If so can I retain the standard in tank pump. Otherwise I'll plan to swap it for a Walbro.


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    When I start stripping the truck down I want to get it done as quickly as possible so I'm trying to get everything planned out first.

    The parts list I have so far is:
    • Engine mount adapter plates
    • Electric fan conversion
    • Exhaust mods
    • Cooling system hoses
    • Fuel hoses
    • Wiring mods
    What issues might I run into?
     
  2. skylark

    skylark I'm Awesome

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    Pretty straight forward swap. Consider a comp 212/218 low lift cam with Z06 springs. You won't be disappointed. Is your new engine a return style fuel system? If so you can buy adapters for the fuel lines. If return less you will need a fuel pressure regulator and appropriate lines. You need the higher pressure pump. I BELIEVE that all 400's used 40 pulse per mile. It seems like there is a setting in the pcm that has to be changed in order for the tach to work correctly on 95+. You will want the longer throttle and cruise control cables from a 96-98 vortec truck.
     
  3. gothicsera

    gothicsera OBS Enthusiast

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    Great, thanks for your help!

    I'll probably skip the cam, but it depends how funds go in the next couple of months. They are the best part of $550 by the time they are shipped to the UK. :(

    It has a return fuel set up, so should be pretty simple, it has the fuel rail mounted regulator.

    I'll have a look for a fuel pump - will pretty much any in-tank, high pressure pump fit in the stock sender unit?

    I'll check out the cruise and throttle cables too. To be fair the cruise control doesn't work anyway, so I might not bother with that!
     
  4. skylark

    skylark I'm Awesome

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    I wouldn't say any pump. The walbro is pretty much a drop in an and the ac Delco ep381 is a drop in as well (96 vortec pump). I know shipping is a killer. Perhaps one well planned order through summit?
     
  5. gothicsera

    gothicsera OBS Enthusiast

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    Thanks again. Will take a look.

    Any idea on a part number for the cables? Having no luck finding them on rock auto....
     
  6. 95SUBURBANLM7

    95SUBURBANLM7 OBS Enthusiast

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    Have you found out what you are going to do with your VSS? I'm doing basiuclty the same swap (Im using a NV4500), but I am stuck at what to do with the VSS. The LS harness has the VSS and the truck has the VSS going to the C100 connector coming from the transfer case.

    Im thinking they get spliced together, but I dont know.

    Good luck on your swap!
     
  7. gothicsera

    gothicsera OBS Enthusiast

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    I'm going to splice the transfer case VSS into the original sensor connector on the LM7 loom. Both should be 40 pulses per rev so it should work fine. You also need to hook up a wire to the PCM to tell it that the transfer case is in low range.

    I now have the motor, trans and harness back at my workshop. Pulled the heads off the motor, very minor bit of water damage in one of the bores. I think it will hone out so just a new set of rings needed. While it's apart I'll replace the main and rod bearings too, seems silly not to really.

    Other than that it looks to be a good clean example of a 2002 5.3....

    The AC pump is siezed solid, and I don't have a mount for the alternator, although I do have the alternator itself! The PCM is the wrong one, has 4 smaller connectors rather than 2 large ones. Hopefully I can sell the one I have and pick up the correct one easily enough.

    I started to re-pin the harness as well based on the info from the LT1 swap site which is excellent. Still a lot to do, but it's set to rain for a couple of days, so I might get that finished....

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  8. gothicsera

    gothicsera OBS Enthusiast

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    More progress on the harness this afternoon. All of the extra wires have been traced and removed. All that's left to do is put in the wires for TPS and IAC as I converted from DBW to cable throttle. Then I need to fit a fuse and relay box and wrap it all up again.

    The connectors for the transmission range switch are damaged, but I should be able to replace them easily enough.

    A pretty straightforward job, just needed a bit of patience. I just worked on one circuit at a time and labelled cables as I went, as there are a lot which are the same color....

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  9. gothicsera

    gothicsera OBS Enthusiast

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    It's been raining here again - the UK weather sucks!

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    I've more or less finished the harness off, I just need to finally wrap it up and check the layout of all the connections. I should be able to do that tomorrow.

    I then spent an hour working on the motor, starting to strip it down for inspection and rebuild. I know it's had water in it, so I'm going to tear it down completely.

    Removing the fan and clutch wasn't easy. I ended up making a holding tool from some flat stock that I bolted to the holes in the front of the water pump pulley, then used my largest adjustable wrench and a large hammer to undo it.

    Removed the intake. Need to swap the throttle body for a cable one if I can find one.

    The EVAP/purge solenoid is broken, but I won't be using it anyway.

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  10. 95SUBURBANLM7

    95SUBURBANLM7 OBS Enthusiast

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    Congrats on finishing your harness. Im almost a year into it and still havent finished :mad::banghead:

    So you say that you spliced the transfer case VSS into the LM7's VSS. So the VSS is still connected to the C100 bulkhead connector, right?

    One of the many wires that I have left, is the purple wire that goes to the ABS module. Was that loose when you spliced the two harnesses together?

    Thanks for the help!
     

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