I've got a stock 305 TBI with 700R4 auto tranny, and im debating on swapping a big block into my Firebird. i dont want to ruin the stock appearance so theres no way im going with big cowl hoods and all that, and i dont want to put a manual tranny in just because the car came stock with auto, and im not putting some ugly gay shifter in either. so im wondering what i can do to turn this little 305 tire spinner into a rubber layin street monster, im aiming for 400hp, but i want to keep my stock appearance! been thinking about an old Pontiac 455ci SD or even a 400ci, i dont want to go down the usual 350ci road, everybodys got that, but i dont know if i could use my 700R4 tranny still, or if i could even fit a 400/455 in comfortably while still keeping the stock hood and not chopping apart my engine compartment. any suggestions/info? has anyone done this before?

 

Check this out if you want to go the Pontiac route. Its not an easy or cheap swap to do, but it can be done.

https://www.thirdgen.org/forums/engi...-v8-swaps.html


I would suggest either a big Chevy small block, like a 383 or a 400, or a big block Chevy, like a 427 or 454, if you don't have much experience installing motors that aren't supposed to be there. They are almost a 'bolt-in' deal compared to the Pontiac motors, and will make alot more power for the same or less money.

 

I really doubt you'd be able to find a 455SD in any kinda restoreable shape for a good price since folks with these cars are after them. I'd go with the Chevy drivetrains suggested, plenty to choose from. plenty of parts availability too with these newer motors.

 

You can use your stock 700R4 by utilizing an adapter plate, but why would you want to? The Poncho engine will make mangled metal out of it in no time. As far as keeping you're factory hood, this depends on which intake manifold you decide to go with... whichever one you do though, be sure to use a drop-base air filter.

Good luck.