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454 Swap

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by bigbluesub, Oct 5, 2011.

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  1. bigbluesub

    bigbluesub New Member

    Greetings, I was wondering what all would have to be changed out to switch out the small block with a big block?
  2. Crawdaddy

    Crawdaddy Moderator Staff Member Platinum Contributor 1000 Posts 100 Posts

    Pretty much everything. Transmission, PCM, radiator, wiring harness, pretty much everything has to be changed because you're swapping motors and going from a small block to a big block. Doable, yes. Cost efficient, no.
  3. silveradotrailblazer

    silveradotrailblazer New Member 1000 Posts 100 Posts

    I see it looks like you have a '85 350 with a carb on your truck now. I don't know your budget but have you looked at the GM crate motor HT502, part # 88890534? It has 377 hp at 4,500rpm's and 512 lb-ft of torque at only 3,300 rpm's. Its made for older heavy trucks.
  4. Boonduff

    Boonduff New Member 100 Posts

    Its actually a pretty easy swap, but remember even a stock smog 454 puts out more torque than your stock drivetrain was designed to handle. It may last if you baby it, but run it hard and it will fail. The stock 700r4 can barely stand up to a stock 350. Your NP241 transfercase will probably be ok, but the 10 Bolt axles will not be happy. Like Crawdaddy said not cost efficient, to make the entire truck reliable you'll have to upgrade the whole drivetrain.
    Last edited: Oct 6, 2011
  5. janikphoto

    janikphoto New Member 100 Posts

    First thing I'd change out would be the size of your wallet!
  6. bigbluesub

    bigbluesub New Member

    Thanks, guess it is more work and money than it is worth. I will work on making a torquey smallblock...
  7. Kraziken

    Kraziken New Member 100 Posts

    It is a painful idea, but it is probably cheaper to trade rigs with one that already has a 454 in it. I'm going to guess it is probably a 2500 too, so other side benefits if you choose this path.
  8. silveradotrailblazer

    silveradotrailblazer New Member 1000 Posts 100 Posts

    How about bore and stroking your small block to a 383 or a 406?
  9. bigbluesub

    bigbluesub New Member

    I think that is what I will do. I will find a machine shop and get some estimates to compare vs the crate 383.....
  10. mv86dually

    mv86dually New Member

    It's still possible to find old rusty Chevy Trucks and suburbans that have big blocks. Then you have everything you need for the swap at a reasonable cost

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