[anthonygazz]

hey all, my father and I picked up a 73 firebird and we've decided to make it a nice little showcar. I'm completely unfamiliar with this car and I'm much more useful with modern style cars but I'm excited to get behind this project asap! We have a few questions that have been keeping us stagnant in the process so i thought maybe you fellas/ladies can offer some info/advice. First, we have the option to run either an Ls1, Ls2, stock 350, or bore the 350 to a 455. just looking to hear all your thoughts on which heart you would go with. Also we are toying with the idea of a blower, i have a CTSV and researched putting the little 1.9 eaton on the LS engines but found that the V blower wouldn't work on an LS2 due to the pullies not lining up. Anyone have success supercharging any of these engine styles? If so what modifications needed to be done to support the power. Any engine that is decided on will be completely gone through most likely with forged bottom end and a nice cam. The car wont be tracked, but will be undergo spirited driving very few times a year. Appreciate all who take the time to read and reply

[blue71ta]

Welcome to the PY forums.
I would go with a Pontiac 455. You can start with a 400 block and use a stroker kit.

[anthonygazz]

Originally Posted by blue71ta

Welcome to the PY forums.
I would go with a Pontiac 455. You can start with a 400 block and use a stroker kit.

any particular reason why?

[weranc55]

I'd go with a ls motor.

[bird72]

I have heard there are stroker kits for Poncho 350's. I believe 383 c.i. (?) correct me someone if wrong on CI. That kind of intrigues me. not so much as "the best option" but as a cool thing to do to be different with a block one already has. The kicker then is either modding the typical lopo 350 heads or swapping to better heads. I like the idea of working the original heads (screw in studs, roller, massage for flow, valves, etc). If I keep my 72 it so so spot on original that I could see that route for me. Only visual change is go to a factory 4V intake card and factory style dual snorkel air cleaner. That way, pop the hood, looks factory. Also I would go ram air cast exhaust manifolds. Very clean factory look with 375hp capability I believe, along with great torque.

[TimeWarp]

I think he is referring to being able to stay with the 3" main that the smaller bore engines have (455 uses a 3.25") and that is an advantage for spinning high rpm, but still going for the bigger cubic inches.

If doing an LS you might want to think about going turbo instead of supercharger. You can build way more power if you want to and custom place the turbo for your needs. No belts to keep an eye on, etc.

Or just buy the LS motor I have...its a turbocharged LQ4 block (the one all the turbo builders use), All Pro stage 3 heads built for boost by a professional with turbo and custom dyno tuned computer (800 to the rear wheels, and that was tuned mildly). She was built to handle 1200 hp. Drop her in. lol

I also have my custom built 1200 hp turbocharged 455 for sale in the classifieds here, and THAT is show worthy. Just sayin...lol

http://forums.maxperformanceinc.com/...d.php?t=761839

[anthonygazz]

Originally Posted by TimeWarp

I think he is referring to being able to stay with the 3" main that the smaller bore engines have (455 uses a 3.25") and that is an advantage for spinning high rpm, but still going for the bigger cubic inches.

If doing an LS you might want to think about going turbo instead of supercharger. You can build way more power if you want to and custom place the turbo for your needs. No belts to keep an eye on, etc.

Or just buy the LS motor I have...its a turbocharged LQ4 block (the one all the turbo builders use), All Pro stage 3 heads built for boost by a professional with turbo and custom dyno tuned computer (800 to the rear wheels, and that was tuned mildly). She was built to handle 1200 hp. Drop her in. lol

I also have my custom built 1200 hp turbocharged 455 for sale in the classifieds here, and THAT is show worthy. Just sayin...lol

http://forums.maxperformanceinc.com/...d.php?t=761839

Good god that thing is a work of art! im all about making a big power car, thats what puts a smile on my face and love in my heart lol. unfortunately my father is more into a show more than go type of build here. he shot down the idea of slapping a turbo on it so its basically either bore out the 350 and put an old style blower through the hood or just drop an LS in it. we will be doing a full tubular front with disc brakes and all that so originality isnt the biggest concern. it will have full custom paint custom wheels all that fun stuff as well.

one other thing i was trying to understand is i read somewhere that all the factory pontiac firebird/TA blocks start as the same cast and are then just bored to whatever cubes designated for the model. seems there is some truth to this but not as straightforward as it seems? we dont have any desire to run the stock 350 we would want the 455 but would rather pay for the LS than the 455 if we couldnt convert the 350-455...i hope this is making sense

['ol Pinion head]

A Pontiac 350 is 354 cubes and by boring the block .060, you might be able to get to 365 cubic inches. 350 blocks cannot be bored to accept the next larger Pontiac 3.75" stroke pistons (389's). One of my machine shop buddies and I tried that in the late 90's on two 71 and 72 350 blocks and bored through into the water jackets.

Wanting more cubes in the '73 Bird, pick up a '70-74 Pontiac 400 block and go with one of the stroker kits. You'll end up right at 455 cubes on an .030 400 block

[72projectbird]

Since its just a Firebird go all out! If it was a real T/A I would stay with a 455. An LS with a blower on it will provide ample amounts of fun. And this is coming from a guy with a 455 and an LS powered car. The Poncho power plants are great, they really are, but theres something about the high winding crazy nature of LS plants that I just love. They're quite snappy, build power very easily and the aftermarket support for them is huge! My Dad has a LQ4 in a 69 Camaro with a Th350 behind it and it dynoed @315rwhp on the stock Silverado tune. This is before a simple cam and spring swap which will put it right around the 400rwhp mark. Depending on how you do the swap, it might be a lot cheaper then trying to build a monster Poncho. You could even get a 6.0 out of a truck and throw a blower on that to save some serious cash over buying an ls2. Whatever way you go, you cant go wrong.

They're will be people by the boat load telling you to stay with Poncho power (this is a Pontiac site after all) but in the end go with whatever you know and like. Like I said if it was a real T/A I would say 100% stay with Pontiac power, but since it isn't its free range!

[bird72]

Originally Posted by 'ol Pinion head

A Pontiac 350 is 354 cubes and by boring the block .060, you might be able to get to 365 cubic inches. 350 blocks cannot be bored to accept the next larger Pontiac 3.75" stroke pistons (389's). One of my machine shop buddies and I tried that in the late 90's on two 71 and 72 350 blocks and bored through into the water jackets.

Wanting more cubes in the '73 Bird, pick up a '70-74 Pontiac 400 block and go with one of the stroker kits. You'll end up right at 455 cubes on an .030 400 block

new stuff out there brother Butler 383-413 from 350 block.

http://www.butlerperformance.com/pro...s.html#407_413

['ol Pinion head]

Not for this kid

[anthonygazz]

Originally Posted by 72projectbird

Since its just a Firebird go all out!

exactly what we've been saying, first we wanted to make it a trans am but then i just felt like a poser and we strayed from the idea and i finally convinced him to go down the resto-mod road. i love the Ls engines and im readily available to a LS1 or 2 for cheap. it looks like it will be a lot more work to stick with the poncho and make it how we want it, and it seems to be making more and more sense to go the LS route. a lot of great information so far

[johnta1]

The external size of the Pontiac block is basically the same.
You could find a 400 Pontiac block get a stroker kit that would be around 463 to 473 CID really easy and cheap.

Put a blower on it and it would blow away any of those LS engines.
And basically be bolt in, no modifications or finding little nit-picking pieces to make something else fit.
(hole for blower in hood only mod probably but would need it for either style engine)

It would also bolt to a TH350 or TH400 tranny no problem.
You would have more torque than you would know what to do with.

Or go with the ls and be like thousands of other camarobirds.



BTW, welcome to PY.

[anthonygazz]

Originally Posted by johnta1

The external size of the Pontiac block is basically the same.
You could find a 400 Pontiac block get a stroker kit that would be around 463 to 473 CID really easy and cheap.

Put a blower on it and it would blow away any of those LS engines.
And basically be bolt in, no modifications or finding little nit-picking pieces to make something else fit.
(hole for blower in hood only mod probably but would need it for either style engine)

It would also bolt to a TH350 or TH400 tranny no problem.
You would have more torque than you would know what to do with.

Or go with the ls and be like thousands of other camarobirds.



BTW, welcome to PY.

lol sell me your 5 second motor and ill slap that in
but really that would be a good option and the only thing i have against it is the fact that we have the 350 already and cant use it, if we did stay with the poncho block we would be stroking and blowing the 350... which is what she said (too perfect), and running that but if we are to buy a new motor itll probably be the camarobirds ls swap

[johnta1]

OK, so you don't want to spend any money on the Pontiac engine just on the LS.

Still can stroke the 350 to what someone here said, and with a power adder (blower or turbo, I'd go turbo) would give the LS a run for it's money too with less of a hassle.

But whatever way you go, at least it is a Pontiac body!

[anthonygazz]

not that i dont want to spend money on the pontiac engine its just i can get either Ls motor for about 1000 bucks with lots of extras, the ls2 is the full vette drivetrain also, what would a 400 block run used? or even a 455?

[TimeWarp]

The LS is easier and cheaper to make go fast, lighter, fuel injected if you have the computer, etc. Theres a reason a 100,000 mile LS motor runs and starts like new most of the time, while the old style engines begin to show signs of wear in the cylinders and other parts of the valvetrain. Its newer, and better technology.

Like someone said, you are going to get a lot of people against removing the Pontiac drivetrain here, but there ARE good reasons to go modern IF you want to.

Since you are going to make a change of some sort anyway, they are both good options...choose the one you like best. The LS way you can put a nice overdrive trans in there for better fuel mileage cruising cross country too, while still having lower gearing for good off the line performance.

If you want to head out on road trips at all the LS swap is hard to beat for reliability, fuel mileage, performance, etc. A simple cam change and you are over 400 hp.

[72projectbird]

Originally Posted by anthonygazz

exactly what we've been saying, first we wanted to make it a trans am but then i just felt like a poser and we strayed from the idea and i finally convinced him to go down the resto-mod road. i love the Ls engines and im readily available to a LS1 or 2 for cheap. it looks like it will be a lot more work to stick with the poncho and make it how we want it, and it seems to be making more and more sense to go the LS route. a lot of great information so far

Hey I resemble that remark!

Starting out with a car engine really does help a lot due to already having the right accessory drive and intake. You should paint the engine metallic Pontiac blue.

[TimeWarp]

I don't view clone or tribute trans ams as being posers. You just like the look, go for it. It was just a package on the car...add the package. Not like you are changing VIN #s. Tons of people throw a formula hood on a car because they like the look. I don't worry what other people think too much. Part of the reason I never bought a Lamborghini kit car is because they look cheesy, and have cheesy components. If someone could bolt on a few things to a fiero and make it REALLY look or drive like a Lamborgini I'd buy one!

[anthonygazz]

Originally Posted by TimeWarp

The LS is easier and cheaper to make go fast, lighter, fuel injected if you have the computer, etc. Theres a reason a 100,000 mile LS motor runs and starts like new most of the time, while the old style engines begin to show signs of wear in the cylinders and other parts of the valvetrain. Its newer, and better technology.

Like someone said, you are going to get a lot of people against removing the Pontiac drivetrain here, but there ARE good reasons to go modern IF you want to.

Since you are going to make a change of some sort anyway, they are both good options...choose the one you like best. The LS way you can put a nice overdrive trans in there for better fuel mileage cruising cross country too, while still having lower gearing for good off the line performance.

If you want to head out on road trips at all the LS swap is hard to beat for reliability, fuel mileage, performance, etc. A simple cam change and you are over 400 hp.

very well put and a great response, thanks sir

@72projectbird the car is already metallic blue but its getting a new custom color and were going to dress the engine bay up real nice.

@timewarp your right it is really about the looks but for me having a modded CTSV when i see a regular CTS with V badges it turns me the wrong way lol i ususally follow the encounter by opening the cutouts downshifting and blowing his eardrums out to make the difference very clear to his and mine thats really the only reason i feel that way, i guess if someone dropped the LSA in a regular cts it wouldnt be as bad....idk either way talking oranges to apples here haha