Slant 6 swap 170 to 225

Slant 6 Engines

  1. CommieHook

    CommieHook Member

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    Hey guys, I imagine that this has been asked before, but I thought I would give it a try.
    The 170 in my '65 Valiant has crapped out (cylinder head) and I have a 225 in a trash '74 Duster. The 170 is mated to a 3 on the tree while the 225 has an automatic. I'm just wanting to swap the engines, not the trannies. What if any problems will I run into?
    Thanks!
     
  2. RustyRatRod

    RustyRatRod Weenie idiot loser. FABO Gold Member

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    The crankshaft register is a different size on the later 225. I think that means you will need a flywheel for the 225.
     
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    • slantsixdan

      slantsixdan =..=

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      You'll need to swap the oil pan and pickup tube off the '65 motor onto the '74 motor, and make a spacer to space the exhaust headpipe down an inch or it'll want to hit the floorpan under acceleration (or, better, make a new 2-1/4" headpipe).
       
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      • valiantwagonguy

        valiantwagonguy FABO Gold Member FABO Gold Member

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        The oil pan needs to come from a n early A and the flywheel needs to come from a 67 or later slant . Use the 170 motor mount brackets and mounts and use the earlier ( 64-66 carb ) so the linkage from the gas pedal will work. I'd use the 170 distributor too unless you want to fool around adapting the electronic one to your car. .Other than that it's all the same
         
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        • Slantsix64

          Slantsix64 Well-Known Member

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          Flywheel needs to be from 68 and up, also your exhaust 170 head pipe will be short to connect on the 225. Also you might need to add a pilot bearing in the auto 225 you might or might not depends, i would run the later magnum pilot bearings easy install and over the counter part, good luck!
           
          Last edited: Feb 5, 2020
        • Wyrmrider

          Wyrmrider Well-Known Member

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          see u in march
          jim
          good move
           
        • 65 Cuda 340

          65 Cuda 340 Active Member

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          The slant six crank flange was enlarged 1/4 inch beginning with the 1968 model year. So your 65 flywheel won't bolt up to a 74 crank as is. However, you don't have to change flywheels. Just take your 65 flywheel to a machine shop and have the center hole enlarged to fit the post-67 225 crank. Will work fine. The pilot bushing is a different issue; most automatic transmission cranks - V8 or six - are not fully machined for a pilot bushing. You might luck out and have an automatic-transmission 225 that has a fully machined pilot hole. If not, NAPA used to offer a conversion bushing that would fit in the semi-finished pilot hole in the crank, but I think they are NLA. Not a problem these days, as the readily-available pilot roller bearing that came on manual trans Dakotas and probably others will fit just fine and will work better than the conversion bushing anyway.
           
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