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Thread: a few questions about 94 silverado swap

  1. #1
    Join Date
    Mar 2015

    a few questions about 94 silverado swap

    Ive been considering 5.3 swapping my daily driver
    94 Silverado short bed reg cab 350 tbi 4l60
    Can I use the donor motors AC and PCM ?
    Can i use the stock 94 gauges ?
    Can I run the stock radiator ?
    I plan to keep my transmission for now so I know I need either a new converter or an adaptor plate.
    Also Ive been reading through threads and ive started to get a list of what I would need
    am I missing anything ?
    motor mounts
    ac relocation bracket
    fuel line fittings
    fuel pump ( wallbro 255)
    Fuel filter
    I know I would have to figure out the exhaust past the manifolds
    Thank you in advance

  2. #2
    Join Date
    Mar 2016
    BC Canada
    Yes you can use stock rad. Your stock lower rad hose will work, but use the donor truck top hose.

    You cant use the donor ac unit in its stock location, you'll have to usr your stock one and run an aftermarket bracket.

    Your stock 94 gauges will work fine

  3. #3
    Join Date
    Aug 2014
    First off, read my swap thread listed in my signature, very similar to yours.

    Second, your stock tranny has kickdown based of vacuum I believe? I could be wrong there, but there will be issues running the stock tranny with an LS motor. IMHO, it's easier to go with a new transmission. The 6L80 is an EASY install in your rig. Especially if you can get a donor motor and Trans out of the same vehicle. They don't have to be, but you won't have to deal with the trans and motor having incompatible operating systems in the computers.

    If at all possible, get a GM shop manual for the year/vehicle of your donor motor. My manuals have been worth more than gold.

    You can get a later fuel tank from a Vortec OBS rig and use a stock GM fuel pump. I like going stock where I can...

    Your old PCM is probably trash. The only thing it might be for is the ABS. Some late 94's I've seen have the newer ABS that is controlled by the PCM. If you're lucky, you have the old ABS which has a self contained brain.

    With minor modifications to the radiator and a Vortec style gas tank you can retain the LS style cooling and fuel tank venting. The later charcoal canister bolts right up to a driver side battery bracket. If you don't have that, get it out of a later truck. Moving the battery to the driver's side opens up the passenger side for air intake. A lot of people just plug the purge lines from the heads into the water pump. That works OK, but if you plumb it the way the newer system was designed your cooling efficiency goes up dramatically. I went with the newer overflow tank and plumbed everything like it was a 2012. I can tow a very heavy boat up a mountain in 110 degree weather and my coolant, oil and trans temps never budge off normal. (I do have big oil and trans coolers...)

    The 2012 exhaust manifolds fit perfectly. I ceramic coated mine. Yes, headers are more efficient, but stock manifolds are more durable and just fit better. Plus, just looking at them you can see how they flow MUCH better than stock exhaust manifolds of yesteryear.

    Remember that when you have your exhaust built, the O2 sensors MUST be installed in the top half of the pipe, as close to the exhaust manifolds as is reasonably possible. Many exhaust shops will put them in the bottom half of the pipe for easier access. That will guarantee early failure of your O2 sensors. Moisture condenses in the pipe as it cools down and drips down the pipe. If it drips onto the O2 sensor, that sensor will fail.

    You mention the fuel filter, do make sure you use the corvette one with the built in pressure regulator. There's lot's of information here on that if you weren't aware of that.

    Oh yeah, your stock AC pump will work fine, you don't even have to unhook the hoses. However, the stock hoses are too long and will be in the way of building a stock type air inlet on the passenger side. (Where your battery is now.) It'll work for now if you just run a cone type air filter, but if you want to make it run better with a stock type air filter you'll eventually need custom AC hoses. Also, if you're going to run your motor where it will spin above 5500-6000 rpm you'll need an AC pump shut off at High RPM. The stock AC will grenade eventually if you spin it that fast. You might get away with a smaller pulley on the AC pump, but it's probably cheaper to buy a pump that has a smaller pulley to begin with?

    It's going to cost more than you budget, you're going to need more parts than you prepare for, it will be so worth it. Also, I really can't recommend going with the 6l80 highly enough. Just so much nicer driving than the 4l60. And so easy to install with your swap. It bolts right up to the motor, you use the stock trans mounts. It bolts right up, you don't even mess with the drivelines. The main issue is changing the input shaft on your transfer case. The stock transfer case speedo sensor drives both the stock speedo and your ABS sensor for the rear wheels. (If you have 4 wheel ABS.) Even if you have rod linkage type shifting, it bolts right up to the 6L80. The only issue there is you have to modify the piece that goes from the frame to the tranny. If you don't, it will rattle against the front drive shaft. Worse, under hard acceleration the drive shaft will push on the linkage shifting you into neutral!

    Have fun and good luck!
    Last edited by Nak; 03-07-2018 at 02:31 PM.
    1992 K1500 Blazer.
    L94 & 6L80
    14 Bolt SF axle w/11" brakes & appropriate Combination brake valve, Eaton Trutrac rear posi.
    8000# hidden winch, Rocket Box, KYB Monomax shocks
    285/75R16 Duratracks
    Flat Panel Display Gauge cluster in progress.
    New interior & exterior paint planned.

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