olds 455 in 80 firebird

[rob04gtp]

Originally Posted by MrPbody

The Olds 455 is a good engine. However, the deck height of the block (centerline of crank to deck) is quite a bit higher than that of the 403. Technically speaking, the 403 is a "small block Olds", and the 455 is a "big block". The side mounts should work from the 403. The exhaust will not, due to the added height. I've seen some pretty sad looking headers "beat to fit" a later Firebird with the big Olds. Hood clearance is another issue. If the car is a T/A with the "shaKer", it won't clear.
Be very glad it's not a T-top car if you want to make some power with it. Rattle traps...
And, in answer to the last question, about which engine would be a good one? Pontiac 400 or 455. In many Pontiac peoples' minds, there ARE no others. BTW, the 400 will basically bolt right in where the 301 was. Some variations in brakcets and the mounting shells, but all the main stuff is in the correct places. And well done 400P will stomp a 455 Olds... Wanna talk aout what can be done with 455 Pontiac??? How's mid-10s with street gears, pump gas (93) and a flat tappet cam? They do it all the time.

The pontiac 455 sounds like a motor for me. Are they hard to find?

[volkerc]

Originally Posted by rob04gtp

The pontiac 455 sounds like a motor for me. Are they hard to find?

hard to find, expensive to build. 400 Pontiac gives you more for your money...

[rooster325]

were do i get headers for a 76 firebird with a olds 455

[MrPbody]

I'm a firm believer in the 400 Pontiac. The majority of what we build here are "stroker" 400s (461). I simply mentioined the Pontiac 455 as an alternative because so many are looking for "big" numbers.... Either of the Pontiacs are better choices than any of the Olds engines...

There are no headers specficially for the '76, but the smaller units (1 5/8 or 1 3/4") for a Cutlass will "fit", IF you have the shorter deck (403). Otherwise, "beat-to-fit"...

The taller deck will present exhaust "fitment" problems.

Jim

[just homer]

You can make killer power out of an Olds 455 if you know what you are doing, I've had quite a few of them in various cars ( 1970 442, 1986 Buick Regal etc) and they make tremendous amounts of tire shredding torque. There are some things that you need to do to make them live longer such as putting in oil restrictors to keep the oil in the bottom end so you don't ruin the crank bearings. Mondello performance can tell you everything you'll ever need to know about these engines and should be able to give you some ideas on exhaust etc. Oldsmobile engines is all they do and they are THE Oldsmobile experts , hands down.

The engine mounts should be the same as the 403 or olds 350 but you may need to remove the spacers that are sometimes used between the engine and the mounts when you put them on the 455. The spacers are usually 3/4 inch or so thick and round, placed between the engine and the mount. I had to eliminate these to put the 455 in my Regal when replacing the 403 to get the engine to fit right.

I too would recommend building a 400 Pontiac if you haven't bought an engine yet. It's easier to find parts for this application ( there were a lot of 400 Trans Am's and Firebirds built and there are tons of aftermarket parts for this) and they can make killer power too. You will be rewarded with fewer headaches and a smaller parts bill in the long run.

But hey, I'm one of those guys that doesn't take the easy road either which is why I'm putting the 455 Olds engine from my former Regal into my sons 1977 Firebird this year. I just sold all of my 400 and 455 Pontiac engines when I sold my 67 firebirds so it's either the Olds 455, build up the Pontiac 350 or buy a Chevy engine.

Look into some old Hot Rod magazine articles from a year or two ago and you will find a buid up of a 455 Olds that easily made over 500 hp. that should get the Firebird moving.