Has anybody put a Pontiac 455 in a third gen Trans Am?
I think this would be the ultimate upgrade. I've got a 10:1, 465 cubic inch Pontiac in my '68 Firebird and it's a very serious engine. It's mild mannered enough to putt putt around town, but will fishtail at speed when you floor it! This is probably the torquiest engine I've ever felt. And still runs pump gas!

One of these motors in a third-gen Firebird or Trans Am wouldn't be dimensionally much larger than the stock 305, but would make incredible torque. I don't think it would do very well trying to pass emissions, so a swap like this might be an idea for me once it qualifies for classic plates.

Here's the scenario. There are a lot of Trans Am/Firebirds in my area. A friend of mine has an '82 he was going to give me, before he decided to keep it for a daily driver since it had a fresh rebuild anyway. Another friend keeps trying to sell me the tuned port 5.7 liter GTA he's had for years. That's a pretty car!

One of these days, I'd like to redo my '68. I'd like to buy an all-aluminum "Chief Many Horses" Pontiac big block and build it up to a 542 ci engine. Then I want to yank the BOP 10-bolt and probably get a 9-inch for it. I could see installing the 465 and 10-bolt BOP in a third gen Trans Am or GTA.

Has anyone done this before? Any pics of the conversion? How does it feel in the third gen?

 

A decent handful of people have done it. Try a search

Also go over to the engine swap forum, I think it's a sticky at the top of the page.

 

You can drop any engine into anything with enough time and money. As mentioned above, the Pontiac has already been done. Personally, by the time you're done, it will probably be cheaper to drop in a BBC.

How about a 500 Caddy engine?

 

Heck with the Caddy engine, go with one of the BBC Mountain Motors...aren't there crate engines in the 560+ inches now?

C'mon Steve, you're BBC man, get the guy on the right track

 

Raised exhaust port heads on a BBC are bad enough. I can't imagine trying to stuff a mountain motor, super tall deck block into a factory framed third gen. The 540/565 BBC is about the most you can go with a short deck engine.

565 is a maxed out bore 540 combination. 632 is the more popular large displacement now. 700+ are IHRA prostock engines.

How about a 810 cid IHRA prostock engine built to more milder specs. Instead of 1600 hp, a more streetable 800-900 on pump gas and redlines at only 7000 rpm.

Everyone has to be different. If you want something other than a BBC or SBC, expect to pay a lot more since it's not as common. We have a Pontiac Acadian (Chevette) racing here with a turbo'd V6. The car runs 13's. Not bad for a car that normally runs 20 second 1/4 miles.

 

810ci .....oh my i'm dizzy ...i think all my blood just rushed to my ...

 

Thing is, I've already got the Pontiac 465 built. I was thinking about building a Pontiac-based mountain motor for the Firebird, and then putting the old engine in a 3rd gen.

The nice thing about the 465 (0.040" overbored 455) is that as strong as it is, it's still very streetable. Sure, so are torquey BBC and BBC-based mountain motors, but it's dimensionally much smaller than a BBC and would fit much easier in a tight 3rd-gen engine bay. As hard as my spark plugs are to reach with headers in the IROC now, with a 355 in it, I can't imagine trying to change spark plugs on a BBC in a third gen, let alone trying to find headers that would fit!

Some people go for the mountain motor small blocks, which is good too, but they're also pricey. The cheapest big motor I could probably drop into a third gen would be my already-built 465.
However, the flip side of that coin is that I still have to put together a motor for the 68 Firebird, in that case.

 

This is an engine swap topic, so I'll move from Tech to there.

And, yes, there is a sticky about this subject.

 

Here's a website to a reknown Pontiac engine builder (Bruce Fulper), who also campaigns a Pontiac powered, 9 second Super Stock 3rd gen:

http://www.pontiacpower.com/

Unfortunately there's not much info on the car, but lots of other good Pontiac engine related parts/info.