Buick 350 Swap / AC Box clearance

[brrian]

I'm a couple of weeks away from swapping my Buick 350 into my 81 GP w/ AC. I anticipate needing to clearance the AC box. There's lots of talk about that here but not a lot of pictures. Can anybody share pictures of what they cut out? I'd like to get that taken care of as soon as the V6 is out.

 

[pagrunt]

You shouldn't have any issues. going from a Buick 6 to an 8 only takes up the free space up front like a Chevy 6 to 8 swap. Remember the V6 is the same design as the V8 minus those two cylinders. I know Mr. Sony will chime in saying the same since he rolls with Buick 350 in his Regal.

 

[buick7332]

I put a Pontiac 400 in my 82 Grand Prix with ac and didn't cut out anything.

 

[brrian]

Here it is. These pics will probably work.
Also referenced here, but the pics are dead.

 

[78Regal350]

In all the digging I did leading up to my swap (which you referenced in the first link above), I seemed to see a lot of mixed information, but it made me fairly optimistic that the heater box modifications could/would be minimal. Obviously in my case that wasn’t true. Another common train of thought was that swaps to larger engines (even BBC) using the non-A/C heater box required no modifications to the box. And again in my case, this wasn’t true.

I’m pretty confident my experience was a “worst case scenario”, but my advice would be to check the fitment/clearance before you start cutting away at the heater box. In many ways the 3.8 is just “a Buick 350 with 2 less cylinders”, but in reality the 350 has a taller deck height and is noticeably wider, which can make this swap a bit tricky.

Here’s a shot from above showing how close the valve cover would’ve been to the heater core inside the A/C heater box.

This picture shows the interference I had between the 350 valve cover and the non-A/C heater box.

This is a rough mockup I ended up with after modifying the non-A/C box so the valve cover could be removed for future maintenance purposes.

This is what I ended up with. Even with removing a sizable section of the non-A/C box I can just barely get the valve cover off the engine.

 

[78Regal350]

I didn’t take a ton of pics when I was trying to fit the 350 with the A/C heater box, but here’s all of what I have (a few of which are in the build thread).

 

[joesregalproject]

brrian is this the same Buick 350 you got from me a year or two ago?

 

[brrian]

No - it's a complete, running one I bought a couple of months ago after I got tired of dealing with some issues with my V6. It'll be bone stock & I think down the road I'll build yours & swap it in.

 

[stew86MCSS396]

I don't recall having to notch the a/c box when the Buick 455 went into the '81 Regal I used to own. Too many engines here but leaning at Poncho engine into a '85 caballero. Still own the 396 out of my SS...that's another possibility but neither of these options require notching the a/c box. 😎

 

[350Regal]

I have a buick 350 in my regal, im using the cast aluminum poston valve covers. I had to cut my heater core with a hack saw one direction and solder it shut went from a rectangle to an L shape. In the fall temps it still works good. Looks sorta about right in the pictures. This year i switch to HR parts and stuff poly mounts. Josh

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