Hey guys, I have an 81 Regal with a stock Pontiac or Buick engine I've never seen, I was told it'* a 1969 Pontiac 400, but I was also told it was a Buick 400, I can take pictures if you guys want.

Anyways, I have a tuned-up chevy 350 engine and would like to put it in. I wanted to know if it was a plug n play deal, or if I have to put in new mounts.

The 400 was installed incorrectly, and has an incline, it also turns off if you rev it too hard.

if the distributor is in the back its not a buick
the chevy engine would not fit unless there is one of those multi fit turbo 350 transmissions they made
trans dap or some others makes a adapter to fit the transmission its just a steel plate
I used one before for a Pontiac to chevy trans swap
eng mounts are different frame mounts might work

Distributor is in the back, I managed to post pictures

I would say its a stock Pontiac 301 that came stock in the car with a turbo 200 a Pontiac 455 would be a bolt in swap they have 2 sets of motor mount bolts on them the 400 only had 1 set on the block and the turbo 200 and 7 1/2 rear end would live if you did not do burn outs the intake wont work as the 455 is 1 inch taller block exhaust would bolt up but might need to be modified being the block is taller
I put one in a 78 grand prix that came with a 301 and turbo 200 and 7 1/2 rear end
it was a torque monster and the transmission and rear end lived as long as its not abused

Brother, you wouldn't believe how much you've cleared up this monstrous mess of erroneous data. The one who sold me the car told me it was a sixties pontiac 400. I've only ever worked on clunky x-bodies, and some ford crown vics, so my knowledge extends to just chevy and ford 5.0l engines. My neighbour, who prides himself in knowing and supposedly working on every gm car in existence, told me it was a buick 400 big block. It works extremely well, despite its ratty appearance, its not from this car, however. I checked the Vin code, this one had an ls2.

my 1978 grand prix had a 4 barrel carb so maybe that would help with some get up and go for you and keep what you have and there was a turbo version that came in Pontiac firebirds
if you want rpm go with the small block chevy
the 455 is more of floor board and go in drive monster
all so a other bolt in that revs that'* overlooked would be a 403 olds eng

I guess I would like to just have a daily driver with a little bit of kick to it for now. I might slowly turn it show-worthy, but for now, making it work reliably is what I'm aiming for.

I'm going to open it up and install everything correctly, there'* many things cheap, wonky, and lazily installed. The cables are all over the place and that drives me crazy. Going to probably follow your example and put in a 4 barrel, mostly because I loved how my Holley-powered 350 moved

you will have to use the factory 4 barrel manifold no after market one will fit the block has a lower deck height
then the other Pontiac engs