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1985 engine swap how do I know what fits?

Discussion in 'TBI & EFI Conversions' started by HalfPynt, Nov 13, 2020.

  1. HalfPynt

    HalfPynt Junior Member

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    Half
    Truck Year:
    1985
    Truck Model:
    C20
    Engine Size:
    350
    I have a tired 350 sb out of an 85 Chevy scottsdale and am looking for another 350 on Craigslist to replace it. How do I make sure I get one that fits? Any and all advice is appreciated!
     
  2. Swearbody

    Swearbody Supporting Member Supporting Member

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    Truck Year:
    84
    Truck Model:
    C1500
    Engine Size:
    355 sbc
    Almost Any 350 from 1955-1996ish will "fit". Some are better than others as far as robustness and power production. The 80's were a hodge podge of emissions and electronic carburation so youll probably need to keep some of the original parts to make the swap work unless you find an exact matching donor. Even if it comes from an 85 it may still be optioned differently due to CAFE restrictions. There were a lot of first tries and hail mary's being thrown by manufacturers to keep mpg in compliance. Cali was and still is the worst.

    I would suggest focusing more on finding a well built or warrantied motor and doing the necessary conversions to make it work in your application. In the long run you will be happier. Most people end up removing all the emissions anyway since its all antiquated and it makes the 350 anemic.

    That being said if you just want to pull and drop then grab one from a c10 that has the same setup. Ill warn you though that 85 was a transition year and the accoutrements like carb, distributor and such are just plain horrible. They were trying to use electronics before electronics became any good.

    Also be aware that transmissions could be different as well so make sure you keep all the original trans related stuff intact. Hell keep it all intact til its swapped and working. Never know what you may need off the old motor like bolts,brackets,etc(from experience)
     
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  3. Paladin

    Paladin "LET"S ROLL"

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    First Name:
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    Truck Year:
    1985
    Truck Model:
    C30 Silverado Crew Cab Dually
    Engine Size:
    468
    Big Block!!!:cheers:
     
  4. 82sbshortbed

    82sbshortbed Fuckemall!!

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    X2 BBC :burnout:
     
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  5. idahovette

    idahovette Full Access Member

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    I'd really like to find a 1955 350, bet they would be worth a TON!!!
     
  6. Swearbody

    Swearbody Supporting Member Supporting Member

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    Ok yeah you got me. The sbc was introduced in 55 but the 350 not til 67-8. I dont know what I was thinking...well yeah I do. I thought sbc and just went to 55,LOL
     
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  7. HalfPynt

    HalfPynt Junior Member

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    Truck Year:
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    Truck Model:
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    Engine Size:
    350
    Thanks for the input guys, I'm looking around right now for a donor truck or junkyard motor. It's what I can afford
     
  8. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

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    Truck Year:
    1981, 1965
    Truck Model:
    81-C20 Silverado Camper Special-TH400-4.10s; 65-C20 with 4:57 gears and Borg Warner Overdrive
    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    Just try to get one that closely resembles what you have. That way all of the brackets will swap over. Keep in mind, looking like you are in CA, you'll need to keep it to where it will pass smog every two years. If it's for the '85 C20, it'll be easier to pass smog.
     
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  9. HalfPynt

    HalfPynt Junior Member

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    Engine Size:
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    I'm registered out of state , so no smog worries...it's a plain Jane sb. Yes I'm in southern cali right now....kinda stuck here too until this truck gets fixed. It's been running on 7 cyl. And sounding more and more ...raggedy.
     
  10. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

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    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    Hey, a V7 is all the rage now, you're trending big time...lol...
     
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  11. HalfPynt

    HalfPynt Junior Member

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    Got my eye on a donor truck, it's a 78 3500 Sierra, looks the same except the oil stick is on the driver's side whereas my 84 3/4 350 dipstick is on passenger side. I'm looking for a local guy to take a look with me because I'm obviously green.
     
  12. Bextreme04

    Bextreme04 Full Access Member

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    The 68-~87 350's will all swap right in. You'll be able to swap everything over including intake and all smog stuff if you wanted.

    87-95 350 will also swap right in with you just needing to get an aftermarket carb intake for a TBI bolt pattern or drilling out the center bolts on your factory intake.

    Your best bet if you can find one though would be a 96-99 L31 350. They would have come in the Suburbans, Tahoes, silveradoes, and express vans in those years. Everything should also swap right over to one of those engines with you just needing to get an aftermarket Vortec Carburetor intake manifold. Those engines will have WAY more power than the 70's-80's 350's and came stock with Vortec heads, single piece rear main seal, and a roller cam.
     
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  13. HalfPynt

    HalfPynt Junior Member

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    Truck Model:
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    Engine Size:
    350
    Yeah, well i ended up with a 1978(?) Donor truck with a 350. I just bought the truck, so haven't even started any actual work yet. Are there things I should do before actually tearing it out and swapping? It has no carb on it. Oh and should I buy a rebuild kit? Or gasket kit? I know my truck has a leaky rear main seal, so I wanna take care of that too while doing all this!
     
  14. DoubleDingo

    DoubleDingo Drain The Swamp, Completely

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    Engine Size:
    Carb'ed Vortec 350; 1972 L48 350
    Since you don't know the condition of the donor, you need to at the very least do a compression check. But if it were me I would pull the heads after I first pulled the engine, and if the cylinders looked good, pull the oil pan. Working on it outside the truck is much easier with it on an engine stand. You can visually check the heads yourself, or have them checked and/or rebuilt at a machine shop. With the oil pan off, check the condition of the bottom end. It wouldn't hurt to check the bearings while you're in there. If it all checks out, replace the rear main seal, and put a fresh oil pump in it, and make sure you torque everything to spec as described in the manual. Then replace all the other seals and gaskets. That engine could be good, or could be crap, but you have no idea until you check it.
     
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