So I decided to rebuild the 401 nailhead and decided that the cost involved was quite a bit more than I was willing to fork out at this time. I had a 350 chevy in the basement and wondered how it would fit under the hood, and one thing led to another from that point. I'm guessing this has been done before in similar Buicks but I just wanted to show what I did and be able to answer questions anyone might have if they're contemplating such a task as this. This engine swap was done basically as a bolt in swap using the original nailhead's turbo 400 (THM 400 to be exact for 64). The oil pan, which I can reply with pictures, was modified to clear the center link, and the oil pickup was modified to position itself further towards the back of the pan, and because thats the only place it would fit. Motor mount plates were fabricated, or cut, from some thick aluminum to bolt to the Chevy block's mount holes. They extend forward to the Buick frame's original engine mounting locations, thus necessitating the use of an electric fuel pump since the pump mounting area on the sbc is blocked by the new engine mount adapter plate on that side. As for adapting the sbc to the nailhead case transmission, I found an adapter that Jeep used from '69-72 or so to adapt the 350 Buick engine to the nailhead case turbo 400 when used in their trucks & Wagoneers. I then used the more commonly available adapter plate to go from the standard BOP trans bolt pattern on the engine side of the adapter down to the chevy's standard bolt pattern. Used a standard GM pwr stg pump in place of the original Buick's pump. Also used a 1-wire type alternator during the conversion to reduce and simplify wiring.
Nice and neat, thanks for the pics. With that fan, and no shroud, I'll be amazed if it dont run hot. Good Luck.
When I read the thread title, I was prepared to not like this, but the way you did it is first class.
Well.... looks nice up top, we haven't seen the pan or mounts yet.... but it does look antiseptically clean, well done!
Thanks for the complements guys, most everything here was stuff I already had and/or leftovers from other projects. I had bought the engine several years ago for just a few hundred dollars. Its probably a fairly low compression 4-bolt main 1975 350 engine that was a reman motor at one time, as its been bored .040", and everything turned .010". It had a couple issues but I went thru it and it runs fine other than smoking more than I'd like. Could be worn valve guides, but I can always swap heads to another pair. I think the only thing I had to buy that you see in the photos was the intake (used), alternator & mounting bracket, and pwr stg pump bracket. Radiator was a used swap meet find that measured as a perfect fit in place of the original. The radiator is actually for a 64-67 Nova. I just had to cut out the upper radiator retainer plate to clear the cap. I havn't noticed it heating up at all and most of my driving last couple weeks was in 80's
You certainly made it more difficult by using all the trans adapters. A Chevy T400 should bolt in the place where the nailhead ST400 is. Overall clean install though and nothing wrong with your adapters, just thought it would be less trouble using a Chevy T400. BTW, those Jeep trans are another source for nailhead pattern T400 cases.
Right you are, and I knew I could have easily used a regular chevy turbo 400, but I'd had the nailhead case trans rebuilt a few years ago and like the way it shifts, so I was pretty set on keeping it if I had a choice. Spent some time one weekend pouring over the Jeep forums to learn about the use of nailhead case turbo 400 transmissions and the Jeep adapter I used was only a half hour from home. I could also have had the guts from the nailhead case trans swapped into a Chevy case as well, but then I'd be making crossmember mods to mount the chevy trans from what I understand.
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