301 to 455 in 79 Grand Prix?

[racingcc]

I want to swap out my 301 for a Pontiac 455. What motor mounts do I need and do I have to remove the heater/ac box on the fire wall? Anything else I have to change other than the trans? Thanks!

 

[Bonnewagon]

Just use the 301 mounts. It will fit with the AC box, but be careful when you swing the motor in. It is REALLY easy to smash into it. The trans will bolt right up too, is it a T-350? No problem.

 

[G-Body_Vet]

Should be a piece of cake since you already have the 301. I'm going from a 305 to a Pontiac 455 in my '78. Keep us updated on the progress!

 

[racingcc]

No. I don't have the correct trans yet. It has a 200 metric boat anchor. Thanks for the tips. Have more let me know!

 

[Don57]

Are you planning on using headers? If not, you should use the 455 exhaust manifolds. The 301 manifolds will bolt up, but the outlet angle will bring your exhaust pipe too close to the chassis. They are fine for the 301 as this engine is not as wide as the 400/455. Ditto on the 301 mounts.