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mp67riv

65 Sportwagon Engine Swap

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Any thoughts about whats involved in swapping a 401 Nailhead and TH400 into a 65 Sportwagon? Given that the 65 Skylark GS had the 401, I expect it will fit in the engine bay with no problem. I assume the GS heavy duty radiator or something similar will be needed. Am curious about changes to driveshaft, rear end, transmission tunnel, suspension, etc...

I'm looking to make it a stronger tow vehicle...not trying to race it...but the gravy is that it should be reasonably quick with a transplant like this...

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I know that the '65 Skylark GS has to have a supplemental plate with each motor mount, to handle the extra torque of the 401. Also, if I'm not mistaken, it has to have its own special exhaust manifold (at least on one side, if I remember correctly), to clear the steering column. The '65 GS also had a stronger, "box" frame, whereas the regular '65 Skylarks have a frame that is open on one or more sides. I'm a little uncertain what type of frame the regular '65 Skylark has because I've never owned one, but I have owned a '65 GS.

Pete Phillips, BCA #7338

Leonard, TX.

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As Pete mentioned, there are special mounts needed to install the 401. The engine mounts consist of cast iron plates that attach to the block , a vulcanized motor mount and a cast iron piece that bolts to the cross member. In short, there are three separate pieces for each side to mount the 401 in a '65 Skylark.  You would also need the GS exhaust manifolds or headers for clearances for frame , steering and cowl. 

Now that we've got the engine in, you still need to make it run.  The starter for a 401 is on the driver side. The starter for a v6 or 300 v8 is on the passenger side. That said, the battery is on the normally on the same side as the starter , so now the battery needs to be moved. There are differences in the wiring harnesses for the engine and the lighting when going from a v6 or 300 v8 to the 401. As for cooling , the 401 needs a bit more radiator then the v6 or 300v8. Early production '65 Skylarks used a down flow radiator. The later production Skylarks used a cross flow radiator. Those early Skylarks also had a different core support then the later production cars and a cross flow radiator will not fit in the early production core support.

 The rear axle in a Sport wagon has the same bearings as a GS. The Skylark uses a smaller bearing . So, the axle of the Sportwagon will handle the 401. I don't recall if the Sportwagon has a boxed frame.

 Using a TH400 should not require modification to the tunnel. Installing a 401 will require heavier springs to be installed in the front suspension. As for the drive shaft, my guess is that it may be strong enough but may need modification to length .

The engine mounts and exhaust needed are '65 / '66 GS specific, fairly difficult to come by and can be costly. Another option would be installing a 455. The mounts to adapt a 455 into an A body like the Sportwagon are reproduced and readily available.

 

 Almost forgot, the brake system would need to be upgraded too. The front brakes for a GS use a larger diameter wheel cylinder then the Skylark.

 

  Loren

Edited by Loren@65GS.com
added information (see edit history)
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Loren and Pete,

 

Thanks much for your insights. This information is extremely helpful. I was thinking of upgrading the front brakes to discs, and suspected that heavier front springs and radiator would be needed. I'll see what I can find out about the frame. I expect I'll be back to you with other questions if I decide to take on this project. I think the Sportwagon would be a really cool tow vehicle if I could make it robust enough. Not to mention they were among the nicest wagons Buick built.

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On 11/22/2019 at 8:26 PM, SBRMD said:

The Sportwagon frame is indeed boxed.

Thanks Steve, 

 I suspected so , but my poor memory couldn't accurately recall. 

 

On 11/22/2019 at 8:38 AM, mp67riv said:

Loren and Pete,

 

Thanks much for your insights. This information is extremely helpful. I was thinking of upgrading the front brakes to discs, and suspected that heavier front springs and radiator would be needed. I'll see what I can find out about the frame. I expect I'll be back to you with other questions if I decide to take on this project. I think the Sportwagon would be a really cool tow vehicle if I could make it robust enough. Not to mention they were among the nicest wagons Buick built.

 

 mp67riv,

  

  Disc brakes definitely would be a good call. I've done that conversion to one of my '65 Skylarks as have many A body owners have. Should you decide to take on the Sportwagon, I invite you to join us over on 65GS.com.  Lot's of good information on the '64-'66 Buick A bodies. We even have a section for wagons. 

 

  Loren

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