olds 307 to olds 350 swap.

Discussion in 'General Automotive Tech' started by zzzizxz, Mar 19, 2016.

  1. zzzizxz

    zzzizxz Well-Known Member

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    Hey all,

    I'm planning on swapping out my 307 for a 350 in my 81 safari.

    (Yes, I know that the chevy 350 is more common, and an LT1 is newer and better, but I don't want the hassle of switching all the components, brackets, etc...)

    My question is this. My mechanic can find a used 350 with ~35k miles on it, and can swap it our for about $2800, or I can get a new crate 350 put in for about $4800.

    Pretending price isn't in play, is there any reason I should be concerned with putting in a low mileage used motor?
    Obviously, $2k is a pretty big difference, but will I regret not spending the additional $2k for new sometime down the road?

    Thoughts?

    Thanks!
     
  2. ModelT1

    ModelT1 Still Lost in the 50's

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    Apparently crate motors went way up. I'd shop around first. My son buys used late model complete engines at the U-Pull-It for $500 or less. True most have 100,000 miles on them. His last cost $250 half price with TBI and he got all the wiring , computer, etc for just a bit more.
    It's all Greek to me but he gets 24+ MPG.

    Personally I'd go for a lower priced Chevy 350 crate motor and not worry about anything.
     
  3. joe_padavano

    joe_padavano Well-Known Member

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    First, you can't get a "new" Olds motor in a crate anywhere, unless you stumble onto an N.O.S. one from a dealership that closed (there WAS one on ebay a while ago). All the incorrectly-named "crate" motors you will find are just rebuilds. $2800 to install a used motor seems high, but I do it myself, so I don't have a feel for the labor costs.

    Be aware that you will want to ditch the CCC system and run a conventional carb and distributor on your 350. That means that emissions controls and trans converter lockup won't work anymore, if you care. The Olds 350 and 307 are externally identical, so this is a complete bolt-in. It should take less than a weekend. I will suggest that while the 350 is out, replace the timing chain and gear. Olds used a nylon cam gear that disintegrates at about 80,000 miles. It's a lot easier to replace on the engine stand. Of course, that's when the MIGHTASWELLS kick in...

    You MIGHTASWELL replace the rear main seal, and since the oil pan has to come off for that, you MIGHTASWELL replace the oil pump, etc, etc...
     
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  4. BlueVista

    BlueVista Well-Known Member Charter Member

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    If the guy can do a rebuilt Olds 350 for 4800 bucks complete it's too good of a deal to pass up. Where is this guy "finding" 35 thousand mile Olds 350 engines? Sometimes those low mileage engines are just sludge monsters inside, short trips and never heat up enough, oil changes every ten thousand miles/ten years.
     
  5. joe_padavano

    joe_padavano Well-Known Member

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    Keep in mind that the last Olds 350 gas engine left the factory in the 1980 model year. Those last few years (1977-1980) were lightweight castings with very low compression, also.
     
  6. ModelT1

    ModelT1 Still Lost in the 50's

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    you MIGHTASWELL swap to a new 350 Chevy and get it over with. Shouldn't take much to adapt motor and tranny mounts. I also am a do it myselfer or get friends to do the work so have no idea what over priced garages charge.
    Keep in mind, they will find things to rasie the price before it's finished.
     
  7. joe_padavano

    joe_padavano Well-Known Member

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    ZZZZZZZZZZ.....

    Not everyone wants a belly-button motor. Heck, even Chevy put Olds motors in their B-body wagons (like my 86).

    Personally, I'd go with a Pontiac motor in a Safari, but the Olds 350 you can install in your sleep.
     
  8. ModelT1

    ModelT1 Still Lost in the 50's

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    Finding a good one ready to drop in is the problem. Belly button motors can be doctored up to look like an Olds.
     
  9. Vista

    Vista Well-Known Member

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    Not all Olds 350's are the same. #5, 6, & 7 heads breathe the best. I wouldn't worry about the later light-weight castings on a street engine. Compression in Olds engines was controlled mainly by piston dish.
     
  10. joe_padavano

    joe_padavano Well-Known Member

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    Why would I want an engine that embarrassed me so much, I had to make it wear a disguise?

    [​IMG]
     
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  11. ModelT1

    ModelT1 Still Lost in the 50's

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    Close the hood and no one else will know.:rofl:
     
  12. Silvertwinkiehobo

    Silvertwinkiehobo "Everything that breaks starts with 'F.'"

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    If the trans has a UniBolt bellhousing, swapping in what your heart desires is, seriously, almost no problem. I've seen a Poncho 455 backed by a UniBolt trans in a '70 Skylark 2-door.
     
  13. joe_padavano

    joe_padavano Well-Known Member

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    I guess that's why all the Chebby-powered street rods have those ridiculous engine covers now. :eek:

    [​IMG]

    [​IMG]
     
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  14. ModelT1

    ModelT1 Still Lost in the 50's

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    I agree, they are silly and ugly.
    I'd say whatever the owner wants to do. It's his money.
     
  15. zzzizxz

    zzzizxz Well-Known Member

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    Why do you say I don't want to go with the CCC with the 350??

    The MIGHTASWELLS are why I'm thinking about going with the gently used, rather than new. If I budget $5k, then I can get the used, and still be able to replace a lot of things while the Engine's out, one of which is a new steering box to try to fix some of the sloppy steering.
     
    Last edited: Mar 21, 2016

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