Your 400 plan sounds good and keeps it all Pontiac.

A Chevy 454 is close to a bolt in as the basic body was also the basis for the Camaro. The change would require wiring as the starter is on the right side, Chevy mount provisions, an adapter to bolt the Buick, Oldsmobile, Pontiac (BOP) bell housing to the Chevrolet block and of course an exhaust system.

Bogie

 

Thanks man.
seems like the chevy is the best bang for the buck here. Even if it hurts a bit to put a chevy in “the ol’ gal”…..

 

If your gonna swap, have you thought about an LS instead??
Might make a lot more sense than a BBC...

 

Going down the road to swap havent been a straight one, and am not sure what to do about that.
Did some calculations yesterday and the budget of 4000USD is gonna be busted fairly easy if i will build a pontiac from scratch. Even if that is my no1 option, i need to be realistic and see that i wont be able to that ammount of money on "a fun thing to do".
I guess a BBC or a LS will end somewhere about 3-5000USD, and that is just over what the heads for the pontiac will cost me shipped and taxed.

Will the LS go more or less straight in as well ?

 

No the LS is more complicated to install and of course requires a computer and all the wiring associated with these all electronically managed engines. Great power and fuel economy but a pretty big step up in technology.

Bogie

 

If i go down the road of LS i think i will go for an intake that will accept a carburetor. Guess that will take away quite alot of the electrical and computer things

 

Loose the computer and you loose the spark. So you need a "box" to control spark. You also loose port injection which is a nice upgrade most guys were drooling over before the LS came out. In stock form NA you can run the LS off half a dozen wires once the VATS(and preferably EGR) have been removed.
You need around 60psi fuel pressure and eventually hooking up the two upstream 02 sensors.

$3000 is a good budget to put a 160-180k 5.3 under the hood of most rides. The engines wiith harness and ecm can be had for around $500 then you ned to flash the ecm removing the vats and egr as well as removing the rear o2 sensors which is around $100-$200. Fuel pump is going to cost you around $200, fuel filters and lines another $200, motor mounts around $300, manifolds/headers around $500 and $100 to hook up the throttle cable. Then you add 1/3 to the budget for all the unknowns and you end up around $3000.

Once it is in with a stock 300hp then you get into stuff that will require tuning. A megasquirt 3 will let you tune and do a huge amount with a ls. Want to run it as a flex fuel engine? Easy. Want to run a shot of nitrous? Easy. Want to run 6-10psi on the factory bottom end? Easy. You could simply install a cam and different/modified heads to bump up the compression running the engine NA on e85 and make great torque. Of course the best parts mean nothing without the best tuning to make those parts all work together.
A megasquirt 3"pro" can make that happen. Good amount to the budget and your going to need a few tools like wire crimpers, pins, maybe few basic electrical tools to check sensor resistance etc. But the thing about a ls is that anything you can think of has already been done with this engine. You can basically roam around on the megasquirt forums and find your perfect 5.3 build and even a downloadable tune for that build in some cases. Megasquirt can be daunting in all the things you can do with it. But if all you want to do is drive then you can get a tune thats pretty close to perfect and then slowly dip your feet into the water with small(reversable) changes. Megasquirt saves every tune and in most cases every change. So if you do mess something up you can simply go back to a previous tune where things were not messed up.


Cadillac, Buick, and Pontiac engines are cool. But you know they can get real expensive real fast even more expensive if you want to run over 4500rpm. MTS, Cadco, TA, and several others have a couple grand from me over the years because I was to stubborn to swap in something I knew would give me more power for the dollar. It is hard to beat an LS.
To beyond stock you can plan around $2000 to upgrade the electronics/software plus the cost of any hardware like a turbo or nitrous kit so lets say $2000 there. But what you get for that now $7000 setup is a turbocharged engine that will make more torque then most built old school big blocks and if you throw a rod out the side pushing 16 psi into a engine really built for a max of 8psi(stock bottom end) you can pick up another short block for $500.

$7000 might sound like a lot. But a built Pontiac engine is easily going to run you at or above $7000 and it wont have anywhere near the streetablity of a $7000 megasquirted, turbocharged, LS engine.

You can also upgrade your build in stages, get the thing running NA in stock form figuring out all the things to figure out with a swap. Then a few months later you can drop in a megasquirt and play around tuning the engine with the stock cam learning. Then you can say put in a different cam or take the plunge into a turbocharged setup.

The thing about being able to tune a engine at your will is you dont need to run around with 550ftlbs all the time. You can turn stuff down for basic driving and when you want to be a bit mean it can be as simple as changing the tune(and maybe a few items like turbo springs). You can easily go from neck snapper to grocery getter in under a hour. Even change the things at a light with things like electronic adjustable blowoff valves(bit expensive though).

On the other end you have a built Pontiac engine where your all in. If you messed up on cam selection or compression or what your realistically going to use the thing for it may only come out of the garage on sunny days when its not going to almost kill the battery to start. And thats a NA engine. If you want to run a bit of nitrous or a turbo on that older engine your going to need to add "boxes" to control things. Even then your risking that $7000 engine if you don't get the tune correct that night at that temp, moisture, elevation, etc.

Guys still do it. But it is a lot safer when you have a computer checking, rechecking, and adjusting in milaseconds instead of you have that one tune and hoping it is "close enough". With a computer you can run closer to the edge of whats safe which often means more power. If things do get unsafe that computer can adjust things quickly minimizing damage. With a carburetor on top of a vacume pump it is going to just keep on sucking even if it is filling one of those cylinders with unburnt fuel. Hydrolock, straight fuel into hot exhaust, or just a massive loss of power its really not your choice and you have no way of changing things if you do even notice it in time to do anything about it.

 

Hey guys.
Been trying to read through the different posts regarding pontiac 400 engines and upgrades, and have ended up with some conclutions.
I am currently planning to build an engine form a non 557 block. Havent found the block yet but am on the look out and have a few interesting subjects, that i might buy if the price is right. To go for a 455 aint an option since it is a quite rare engine to come out for sale, in my part of the world.
The idea is to have a pump gas car that can pack a punch when needed, not race track, maybe +450HP and good torque.

A stroker kit would be another 4-5000USD (parts + shipping+taxes etc) so that is more or less ot of the question at this point, i have a budget for parts etc about 4000USD without shipping and taxes etc, that cost can be added to my budget later on just to make it a bit easier for you guys to help me out with parts. As a rule of thumb taxes and imports is about 1.37x store price and shipping from the US.

What i have planned on doing:

• 400 block with stock crank, zero decking and depending on the state of the block maybe do a .030 bore.
• New pistons and rods.
• KRE-Heads 85 or 74cc with 260cfm flow. need to do some calculations on the CR to see what will be the best option.
• Cam change - Please come with good suggestions, i am thinking flat tappet, but not a must.
• Intake can be stock or a Performer-RPM, depends on what i can fit under the hood of the 71 Firebird.
• Headers to a 2.5 or 3.0" dual exhaust.

Do you have any ideas on what kind of HP and torque i could get out of a build like that ?
Any suggestions on cam?
Any other ideas regarding the engine ?
I guess i need to do something about the rear drive as well, new differential, gearing etc.

Another idea is to take a Big Bock Chevy, since that is a lot more accessable where im at with both engines and parts for them, and try to fit that under the hood. Any ideas on that topic ?
Will it fit straight out with different motor mounts and gearbox ?

Thanks guys!

What about an aftermarket 455 crank in your 400 block.? I think they fit, they are cheap, I don't know how expensive the corresponding rods and pistons are.

 

455 has bigger main journals…. So needs some machine work to make it fit 😒

 

What about a sbc. Poss vortec 350 with some basic mods?? Just a thought. Be nice to keep it pontiac but I think it will get pricey for you. Good luck.

 

Im looking more and more on the LS-Swap. Seems like the most bang for the buck. Even though it would be nice to let her atay all pontiac.

 

I have 3 spare lm7's with one in my build currently. They are everywhere over here and the bottom end will handle 8psi without to many fits.
Its before displacment on demand so swapping one out for another is much easier with less things to remove/modify.
A lm7 is before drive by wire so you have a cable throttlebody.
Of course its not terribly hard to convert to drive by wire if you want the few features that provides like a cleaner firewall and potentially easier cruise control etc.

 

Being in Sweden have you considered converting to electric?

Internal combustion is great. But I imagine your noticing more and more EV running around.

Threw a wrench in the mix. But it is something to at least look into.

 

Seeing your in Sweden go LS, or like Cerial said find a wrecked Tesla S and swap away

 

Swapping for electric aint an option.
not gonna turn this thread into a political debate…. But in shortly the small ”green party” have been able to make terms so another prry could build goverment with their support. That resulted in closed down nuclear planta in the aouth, and thw capacity of the net is to low to be able to send whats needed in the southern parts from the water powerplants in the nort. Power shortage have resulted in absurd electrical bills.

LM7 seems as the most reasonable choice to reach about 450 HP fairly easy.
At an ok cost.
there is allao the option of buying an already built/modified motor, but o ia the fun in that ?
The project it self is a part of the fun for me

 

MSD sells a stand alone ignition controller that allows you to run an LS engine with a carburetor if you want to go that way and avoid all the wiring and sensors needed for fuel injection...
Holley has intakes manifolds, others might too.

MSD 6014 MSD LS Ignition Control - Red (holley.com)

 

Before you look at engine modifications. Make sure anything you do is not going to mess with you emissions/inspection/insurance wise.

Some states over here have crazy rules when it comes to emissions and inspections. If you dont color inside the lines they can basically make it illegal to drive that money pit on the street.
Insurance wise they can charge whatever they feel like if something has been "modified".

I know a 1 ton cab and chassis will cost a considerable amount more to insure then a 1 ton with a flatbed installed in place of the factory bed. Everything else being exactly the same.

Some insurance companies/states dont care if you go from a 100hp 4 cylinder to a 400hp v8. Some only look at cylinder count. "Yea it only has a 4 cylinder"(and 16 pounds of boost). Same with going from auto to manual. I know I tend to drive a manual a bit safer with less braking and I am more aware of my speed. But most insurance companies still look at going from auto to manual as solely performance oriented.

Best to just search around a bit on your local forums(not asking inspectors/insurance directly to avoid being inside cross hairs). Find out whats allowed and what may give you headaches.

 

Before you look at engine modifications. Make sure anything you do is not going to mess with you emissions/inspection/insurance wise.

Some states over here have crazy rules when it comes to emissions and inspections. If you dont color inside the lines they can basically make it illegal to drive that money pit on the street.
Insurance wise they can charge whatever they feel like if something has been "modified".

I know a 1 ton cab and chassis will cost a considerable amount more to insure then a 1 ton with a flatbed installed in place of the factory bed. Everything else being exactly the same.

Some insurance companies/states dont care if you go from a 100hp 4 cylinder to a 400hp v8. Some only look at cylinder count. "Yea it only has a 4 cylinder"(and 16 pounds of boost). Same with going from auto to manual. I know I tend to drive a manual a bit safer with less braking and I am more aware of my speed. But most insurance companies still look at going from auto to manual as solely performance oriented.

Best to just search around a bit on your local forums(not asking inspectors/insurance directly to avoid being inside cross hairs). Find out whats allowed and what may give you headaches.

insurance aint a big problem here for that kind of car. Emissions/inspections/MOT aint a problem since its the rule from when the car was made (this is a 1970 gen2 Firebird) so emissions are quite generous, if i for some reason needed to take it to inspection ( in Sweden cars over 50years old dont need to be inspected, unless police demands it on your specific car)