Swapping a 1992 D150 la 3.9 tbi for a 1989 la 318 tbi to be made carbed

Discussion in 'Engine & Performance' started by T3CH83, Jul 8, 2018.

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  1. T3CH83

    T3CH83 Junior Member

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    Ram Year:
    1992
    Engine:
    la 3.9 v6
    I scored a parts truck roller with no body or engine harness that was a 1989 LA318/727 with tbi and the necessary mounting brackets off of craigslist for $200. The guy only needed the cab.

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    I plan on doing a mild build on the engine before swapping based on a mixture of two popular hotrod.com articles:

    Junkyard Jewel:400hp 318 https://www.google.com/amp/www.hotrod.com/articles/318-small-block-build/amp/ and

    318 Engine Build – A Parts Book 400HP 318 https://www.hotrod.com/articles/mopp-0409-318-engine-build/amp/

    I've already got the 302 swirl port heads on my donor 318 so I plan on attempting a home port job upgrading the valves to the larger 2.02/1.60 with a set of Milodon street valves. However, on the bottom end, I plan upgrading the pistons with hypereutectic 318 pistons (KB 167) and moly rings once I take the block to get inspected/ assessed for bore wear, hot tanked, and zero decked. So for this setup, I would zero deck the block as opposed to the head milling. I also plan on using the Comp Xtreme Energy 268, 224/230 degrees of duration at 0.050 with a 110-degree lobe separation angle and 0.477/0.480-inch lift to make some power. For induction I plan on going with a new eddy performer RPM air gap 7576 from summit and a Demon Carburetion Street Demon Carburetor (1901). For exhaust, Hedman Street Headers 79080 leading to Summit Racing Universal Rod Builder Exhaust Kits SUM-670146 with Flowmaster Super 10 Series Mufflers 842515 exiting before the rear tires, out the sides. The biggest issues / questions that I forsee running into:

    1) Going 3.9 tbi wiring to carburetor leaves so many gaps it seems like I may be forgetting something.. I've got nothing from the donor truck electronically except for the distributor, which for all I know, might need replaced as well and with a new coil, etc, or ignition system altogether.

    2) Will the original 727 behind the old la 3.9 work (linkage and all) or should I roll the dice on the 727 already mated to the 1989 la318?

    3) I'm pretty sure I will need a fuel pressure regulator but aside from that obvious bit, any suggestions in routing / fabing up a working fuel system. I've just recently replaced the fuel pump / sending unit and the fuel gauge came back to life and truck starts without issue.

    4) Can I swap over the front of the la 3.9 v6 (timing cover, brackets, water neck) and use all existing accessories / brackets? The old R-12 ac still works great and was carefully planning on laying everything over to the side during the swap. This way, if it will work, I can retain the serpentine belt system and just swap crank pulleys.

    I intend to use the truck as an occasional daily driver, an occasional light hauler, and primarily for weekend cruising fun or to haul a motorbike around in short distances. This will be my first engine build, first engine swap, and first project vehicle so I hope the experience teaches me well. Please drop by any feedback, knowledge, suggestions, comments, anything you think might help as I'm fairly certain even after late nights Googling research that I'm not considering something or leaving something out. Thanks for the add!
     
    Last edited: Jul 8, 2018
  2. crazzywolfie

    crazzywolfie Senior Member

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    Engine:
    5.2
    are you sure that is a TBI 3.9 because it looks a lot like a mpfi 3.9 magnum. you can try getting a build sheet for the truck. i have a feeling it has a 42RH which is not the greatest trans to have if you are putting power to it but i would probably try it out and see what happens. if it has a 46RH it should hold but since it has the v6 i have a feeling it is a 42RH. worse case scenario is you are swapping out the transmission down the road but the 42RH would be better than the 727 for fuel economy especial with the overdrive and lock up torque converter. you might have to swap linkages with the 727 tho to make it all work or buy an aftermarket kickdown cable kit since the magnums had the linkage on the passenger side of the throttle body.

    the distributor will be different on a carbed engine than it will be for either of the fuel injected engines you have.

    you will need an aftermarket fuel pressure regulator and to buy a pressure switch to control the the fuel pump if you go carbed. http://www.how-to-build-hotrods.com/electric-fuel-pump.html

    i think everything from the 3.9 should swap to the 5.2 but you may need to take everything including th timing cover to make it work. i also think there is only 1 or maybe 2 intakes that might be compatible with a/c.

    have you considered going aftermarket TBI on it? the truck is already setup for fuel injection so it would save you a bit of money since you would really only have to spend money on the TBI unit. you were likely going to spend $300+ on a carb. another $400-$600 and you got fuel injection which will make it more drive able.

    also you may need the motor mount extension plate on the drivers side frame rail. you can see it in the one pic you posted. you will need that to drop a v8 in a v6 truck.
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  3. T3CH83

    T3CH83 Junior Member

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    Thanks crazzywolfie! So after looking further into the truck, it turns out that you are correct. I have the first year 3.9 magnum v6 in my '92 d150. I also have what seems to be the 32RH - A998/A99 from the hood sticker - with the lock up torque converter in the truck currently.

    When I bought the truck, the guy sold it to me super cheap because he thought the OD had gone out. When I noticed no OD switch in the stock location, I knew I had a 3spd. I did about 85 - 90 mph for a short stretch driving it home and yes, it sounded like RAAAAAAAAAA lol. Had to see what I bought you know considering the guy was convinced that the trans wouldn't go into gear since day 1 that he bought it.

    So, any idea what couple of intake choices I might have with the ac going carb? I've looked at the FI Tech systems also. I kinda wonder what kind of power the stock upper end of a magnum 5.2 conversion with mpfi would make.. I'm wanting to make about 400hp, if more inexpensive the better, while keeping ac and possibly going electric fan - especially on the FI Tech path -.

    Thanks for reminding me about that mounting plates also. It's been over a year coming and I'm just now starting to make some progress having to work outside on rented property. Thankfully my landlord lives next door and used to be a bit of a gearhead too.

    Sent from my SM-G965U using Tapatalk
     
  4. crazzywolfie

    crazzywolfie Senior Member

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    you can tell by the keg shaped intake plus 92 was the first year for the 3.9/5.2 magnum engine. i guess if you got the choice between a 32RH and a 36RH you are better off with the 36RH. ya if it had overdrive it would be a better transmission to keep for fuel mileage.

    i am not sure which intakes are compatible. i am almost certain it had to do with where the upper rad hose connects to the intake and being in the wrong position on some intakes so they would be right where the compressor sits. you can kind of compare where the upper rad hose is on the magnum engine is compared to the la engine. pretty big difference in location.

    i am not a big fan of Frankensteining an engine. if you want magnum heads it might be best to just get a complete magnum engine. i do think there might only be 1 magnum carb intake that is a/c compatible. ya fitech has quite a few cool options with there setup.

    no problem. i know how much of a pain it is to do the swap without that plate.
     
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