Hey everyone, new to the group and need some advice. I bought a 67 Firebird project car a few years back. The previous owner wanted to drag race and installed an Olds 425 engine from a 67 Toronado, with a turbo 400 tranny. While it has lots of power, I’m not a fan on this engine and want to swap it out. I put a post on CL to feel our offers and someone replied offering to trade for a 455 that came out Of their 1970 Firebird (with turbo 400 tranny). Don’t have any other info on this engine yet.

Never had or worked on a 455. Are they solid engines? Is it a fairly straight forward install? Will i need to swap tranny’s as well, or will my current tranny bolt right up?

Thanks for any advice and input. I know I’ll need new exhaust headers. I’m just not sure how readily available parts are for the 455 (parts for my Olds 425 are pricey and few options).

I would trade for that 455 all day, every day.
I'd grab it before its gone.
Check the engine numbers first tho.
Engine should pretty much bolt right up, unless they butchered something with the Old set up.
May need a different cross member or driveshaft, again, depending on what they juryrigged...

Awesome, thanks for the advice. I was thinking the same thing. Also had thought that the bell housing for Olds and Pontiac were interchangeable, but wanted to ask and be better safe than sorry. Have no problem buying a new cross member and/driveshaft.

Any suggestions on the radiator? I currently have a 3 core aluminum radiator with dual electric fans. The Olds engine would tend to run a bit hot and the rad setup has a hard time keeping up in the texas heat. Think the 455 will fair better, or should I invest in an upgrade there as well?

I’ll keep everyone posted!

Yup the 455 would be better any day but you have to find out why it's being unloaded. A Pont motor in your bird is gonna be better everyday but don't expect the price of the parts to be any different from the olds stuff. Probably a wash there. Trans should be fine. Same bolt pattern. They never put a 455 in a bird in 70 so it must've come out of something else.
Temp issues are all about the right equipment, the correct setup, and the right adjustments to timing and fuel mixture. There's no magic pill you can buy. It's a process. Do it right and it works. Do it wrong and it'll never work right.

Well the guy with the 455 ghosted me. But did have someone reach out wanting to know if I’d be willing to trade my Olds 425 for his 400 that came out of a 69 Firebird. I’m actually a little more interested in the 400 anyways. Anyone have any thoughts on this swap? Will my TH400 bolt up to this even tho its a smaller engine?

Thanks guys, you’ve been extremely helpful! I’m a former 2nd Gen Camaro guy but secretly have always favored ‘Birds over ‘Maros.

Here’s a pic of my baby. 67 with 68 doors and other misc tweaks. She’s a work-in-progress!

Good looking car. No problem with the 400 bolting up. You probably will be better off with the 400. Depending on the year of the 455 block some will drop right in and some years need adapters for the motor mounts..
Interesting, I thought there was some issue on the door hinges between 7 and 8. 3 mounting bolts on the 7 and 4 on the 8. Apparently they do bolt up.

You’re correct, but the previous owner did a lot of Frankenstein work (a lot of it I’m having to correct) but the doors were actually one of the mods I enjoy. I’ve got it covered atm due to expected rain for the next several days, but I’ll take a look as see if I can offer some insight as to what he did to make it work.

As long as you have the correct engine mounts on the subframe, any 326-455 will drop right in. For a TH400 trans you will need the proper crossmember, they are available aftermarket.

*****UPDATE*****

Decided for the sake of simplicity, to go with a SBC engine. A 350 seems like the most affordable option, however I’ve heard good things about SBC 327s. Will eventually do an LS swap so right now just looking for an easy engine to drop in and I know SBCs are a dime a dozen, so parts are cheap and easy to find, not to mention there are tons if aftermarket options.

That said, SBC 350 vs 327??

Pontiac 326.

Haven’t seen any Poncho 326’s posted but I’ll keep an eye out. Tomorrow I’m going to look at a Poncho 350 w/TH400 tranny that was recently pulled from a 68 GTO. Was apparently bored 60 over, making it a 400? I’ll copy/paste details below. For $800, sounds like a great deail! But open to hearing thoughts from those more informed than myself...

“ Selling the 69 block that came out of my 68 GTO. It’s originally out of a 69 GTO 325hp. Heads are 76 4X big valve heads that are of the tamer street compression. The motor has been bored .60 over and looks to only have well under 10k on it. Good solid bottom end and includes stock and hotter 280 comp cam. Intake, carb, manifolds included. Block was running in the car a few months ago.

The transmission is also coded for a 69 GTO. It’s a TH400 with manual kick down. Includes stock torque converter. Everything has been wrapped and stored indoors.

This combo could easily be retorqued and installed as is. But could also be honed and cleaned too. Up to the buyer and budget. ”

That will make many of us sad. But it’s your car

What will? The Pontiac engine I was just talking about, or putting in a SBC 350?

The SBC

Well, i decided to go with the Pontiac engine/tabby combo described above (originally from a 69 GTO). I’m super excited about it!

Good for you! GTO engine better than a SBC. When you hear that GTO engine in you classic Firebird you will be glad you went with the Pontiac.

I agree with Gus, the torque of the Pontiac engine, no matter what size, makes it a different animal than any chebby.
With all the similarities of the Camaro and the Firebird, It's the engine and the rear end that set them apart. Like you said, the SBCs are a dime a dozen and you can't swing a cat at a car show without hitting a dozen cookie cutter Camaros, if you put a SBC into a Firebird you have a Camaro with slightly different body style. My opinion anyway.