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 Bla de blizhibliz de blatde blizi bla bla 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 Well-Known 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 FABO Gold Member FABO Gold Member

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          see u in march
          jim
          good move
           
        • 65 Cuda 340

          65 Cuda 340 Well-Known 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.
           
        • Pat Caporuscio

          Pat Caporuscio New Member

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          I am doing the same swapping a 1971 225 into a 65 valiant with a 170., want to put the trans in also. Possible?
           
        • Charrlie_S

          Charrlie_S Well-Known Member

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          Yes, but much easier if you keep the early trans. Are they both auto's, or sticks?
           
        • Pat Caporuscio

          Pat Caporuscio New Member

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          Auto, but I put a head on the existing motor in the car and it appears to be a 225. So I will see how it runs with the new head. Will have an extra engine and trans if it runs well.
           
        • Charrlie_S

          Charrlie_S Well-Known Member

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          65-71 auto trans changes that effect a swap.
          1) Shifter change, 65 is cable, 71 is mechanical. Would need a 1966 steering coluum, or 66 up floor shifter. or aftermarket floor shifter.
          2) Drive shaft. 65 had a B&T bolt on flange at the trans. 71 uses a slip spline.
          3) Speedo cable. need a 1966 cable (will fit the 71 trans and the 65 speedo.
          4) Change wiring on neutral safety switch

          That is using a 68 or newer trans (auto) with a 68 or newer slant six.

          If trying to use a 68 or newer auto trans, with a 67 or older slant six, you would need a custom built torque converter, as the pilot hole in the end of the crank got larger in 1968, and the 68 up converter will not fit the 67 down crank. You cannot use the 67 down converter in the 68 up trans as the splines changed between the two years.

          You can use the 67 down trans with a 68 up engine just by using an inexpensive adapter bushing in the end of the 68 crank.

          You must use the flexplate for the year engine, not the year trans.

          Think I covered everything
           
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