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daveh 11-10-2005 08:17 PM

Will An Olds 455 Engine Fit In My 69 Firebird
Hey guys,

I just bought what I thought was a pontiac 455 for my 69 Firebird but what I got was a 455 oldsmobile engine. I know I should have done my research. Anyway I got it and my question is will it fit ok? Do I have to make any unusual modifications? Any help on what to do is appreciated. Thanks


woodz428 11-10-2005 08:27 PM

Unless you have a bell housing for the Olds pattern, that will need changing. I think that the 403 Olds engine (called a corporate engine at the time) was available in some mid to late '70s 'birds, so you should be able to get motor mounts and other parts to set it right in.

techinspector1 11-10-2005 08:28 PM

My son and I put a 455 Olds in a 72 Luv truck for his high school driver, but I've never put one into a Gen1 Firebird. Here's some info I came across, hope it will help.... 11-10-2005 08:36 PM

The subframes on the post 69 Camaro/Firebirds are front steer like the Chevelle and GtO frames. So you may have to fabricate frame mounts for the early rear steer frame. A 455 Olds will fit. As mentioned you will need an Olds compatible trans but any BOP 350/400 turbo should fit. exhaust manifolds or headers might be tuff to find also. As the steering box gets in the way.

I have done 500 Caddys in this combination with nearly all factory parts.

techinspector1 11-10-2005 10:12 PM

"As the steering box gets in the way."

Of course it'll make it tougher to fit passenger side exhaust, but you can move the motor/trans to the passenger side slightly to get some clearance if you need to, just be careful about keeping the centerline of the crank parallel with the centerline of the car to prevent u-joint problems.

On a 302 Ford / 83 Mitsubishi truck swap i did, I moved the motor-trans to the passenger side of the truck 2 1/4" to clear the box.

jimfulco 11-11-2005 01:38 AM

The subframe of the '67-'69 Firebird is basically the same as the '73-74 Olds Omega, which, I believe, was available with an Olds 350 engine. The motor mount position on the Olds 350 is at the same place as on an Olds 455, so you may be able to use the mount system from an Omega with an Olds 350 to mount the Olds 455 in the Firebird subframe.

The '69 Firebird used a metal frame bracket with a rubber & metal mount sandwiched between it and the engine. On the Omega, a solid metal bracket was attached to the engine, and a rubber & metal "clamshell" mount went between the frame & that bracket. The bolt holes in your frame might not be in the right position, but you can drill your own if you need to.

The 455 has a taller deck than the 350, so accessory brackets from the 350 probably won't fit the 455, and you might run into some interference since the 455 is a little wider. It might be easier to just sell the Olds 455 or see if you can find someone with a Pontiac 455 that's willing to swap.

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