454 tbi with 4l85E swap into c1500 350tbi

Discussion in 'Engine Performance + Maintenance' started by Bloodwater79, Jun 29, 2020 at 11:12 AM.

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  1. Bloodwater79

    Bloodwater79 Newbie

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    Have a few questions, didnt know where to start looking.
    I have a full 1994 c3500HD 2wd pickup with a rotten frame, I pulled the 454 and 4l85e out of the truck and I'm wanting to transplant it in my 1993 c1500 2wd, other than the radiator and transcooler, what wil lI need to bring over to make this work? also I didn't know if it would be better to swap the TBI to carb or if that would just add more work? will the serpentine belt setup from the 350 transfer over or will I need to find a setup for the 454? and is it worth transplanting the hydroboost system or is it just over kill?
     
  2. stutaeng

    stutaeng I'm Awesome

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    C3500 HD? the REAL HD with the filler on the front bumper? 14,000 lb GVWR or somewhere around there? That should be the 4L80e, but the 4L80 and 4L85 I believe are identical, just beefed up internal mechanical parts, so no problems there.

    As far as swap into the C1500, it should bolt up with the correct hardware on the engine side. You'll need to modify your transmission crossmember for the 4L80, as it is longer and will need a shortened driveshaft.

    Not sure on the radiator. A member here that's more familiar with 3500HDs knows a lot more on these trucks. Hydroboost is nice, but you are looking at just the valve itself swap, right? Most like the hydrobbost because of the firm pedal feel. The 3500HDs have monster 19.5" wheels...

    I hope this helps.
     
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  3. someotherguy

    someotherguy I'm Awesome

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    If it's a real 3500HD as stutaeng is asking you, those are 15K GVWR trucks and the 4L80E has an extended tailshaft housing with a drum parking brake at the end of it. Not really the best swap candidate for putting into a C1500..

    Most people refer to regular 3500's (and 8 lug 2500's) as HD because GM tended to as well, though that's not the actual model name. So, assuming your 454/4L80E came from a regular 3500, just bring everything over. Engine, trans, engine wiring harness, PCM, radiator/shroud, and fuel pump. Yes, fuel pump. 94 and 95 454's have a higher pressure pump (26-32 psi spec) but it will fit your existing sending unit. Or save yourself some future trouble and just buy a new pump spec'd for the 94 454.

    And yes on the hydroboost. Much better braking power than the vacuum booster.

    No on the serpentine drive bracketry. Small block and big block are not the same.

    Richard
     
  4. Schurkey

    Schurkey I'm Awesome

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    Expect to need ride-height and headlight adjustment. Potentially, you'd want stiffer torsion bars, but "maybe" you can adjust the existing bars to work.
     
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  5. Busted Knuckle

    Busted Knuckle OBS Enthusiast

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    That's a lot of work. Q is whether the wiring harness is the same. Harness also feeds the instrument panel. Do some more research on harness PN. Assuming they are the same the job is easier, just use original harness. ECM pinout needs to be checked. You will probably have to convert the brakes to allow for vacuum vs hydroboost. Pick one. Use the fuel pump from Delphi for a 1996 454 vortec. Change the distributor while its out of the vehicle. Exhaust will be completely different. Also a larger radiator. 454's run really hot. Use a Motorad 180 stat and two bottles of water wetter in a 25%-40% mix of AF and water. IMHO its not worth the money.
     
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  6. stutaeng

    stutaeng I'm Awesome

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    Stiffer coil springs? C1500 didn't have torsion bars, right?

    Actually, did any C1500 come with BBC (except SS, of course) from the factory?I believe there were some C1500 with diesel option? Maybe look into those for parts swapping?
     
  7. someotherguy

    someotherguy I'm Awesome

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    Yep! Just coils up front. Yeah it could benefit from stiffer springs, but that can be figured out with other decisions like desired ride height.

    There's some unusual statements in this post from a couple folks, that's for sure. :D

    Easy swap job. Totally worth it, especially since he has a suitable donor vehicle.

    1993-1994 are so similar in so many ways there are few roadblocks to this particular swap. The engine harness is an EASY swap over, no need to swap the dash harness. There are more than a few differences in the engine harness (esp. the transmission wiring) so moving it over is way easier than trying to hack the existing one. Engine and dash harnesses are two separate items...

    Yes, a few extra parts will be needed to round out the job but that's what's involved in swaps..

    Richard
     
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  8. Schurkey

    Schurkey I'm Awesome

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    Yes, I got caught on coils vs. torsion bars. Point being, adding more weight right over the front wheels is going to sag the original springs, and it's going to screw-up headlight aim. There's a thousand guys who change the ride-height on their trucks, and damn few who think about where the headlights are going to point afterwards.

    Then we have multitudinous threads about how the headlights aren't any good on these trucks, so they "need" to install junk Chinese HIDs or something.
     
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  9. PlayingWithTBI

    PlayingWithTBI Desert Old Guy

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    Hell, just drop in the 454 and then add shackles on the back - instant 2/4 drop!
     
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  10. someotherguy

    someotherguy I'm Awesome

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    The torsion bar thing cracked me up but mostly what I noticed was ol' boy talking about how it was too much work. :D So is changing your own oil, but I do that, too..

    Richard
     

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