Im thinking of buying some in good condition tpi 305 heads , lt1 cam and a carb intake with adapter for my stock 305 tbi.

Will i see any noticable gains from all of this paired with headers down to 3 inch piping to an aftermarket muffler. Like how much hp and torque gains would u guys think i would get out of all this parts compared to stock. Ofc all with the proper chip for all these parts. Also thinking of installing an underdrive pulley kit wich according to them adds about 10 to 17 rwhp but i doubt. Also plan to upgrade my fuel pump to a stock tpi pump since a lot of ppl say that tbi fuel pumps are not good if u plan on better breathing mods.

Also im a little new in all of this but will 1.6 ratio rocker arms help in any way or will i need a whole new kit of springs pushrods etc?

My plans is to atleast have above 225 crank hp in my 305.

I dont plan to make this car a 12 second 1/4 mile race car with just minor bolt ons and stock 305 but i would atleast like to have some kick in my firebird and not get beat by 4 cylinder minivans ( not that i have raced any and got beaten but u know how l03 owners feel when everything is stock , its my second car and i plan on keeping it for a while this thing is so freaking fun to drive and rare i have yet to see any other 3rd gen v8 were i live besides my bro who has a 5 speed GTA 305 tpi.

Speaking about the 305 tpi that came in GTAs irocz etc, why are they rated at 225 HP and other 305 tpis at 195 ? Is it cuz they came with better heads , cam or bigger valves ?

 

The head swap can be triky on a stock bottom end, be aware that a head swap may need to include deck milling the block to allowe correct quench and good sealing at the same time. Too big quench will require a lame SA table, reducing power output.

LT1 cam with 1.6 rockers may move the power band too high for a stock bottom LO3.

To match a 91-92 L98 thirdgen with full exhaust, you need: full exhaust, LT1/LT4 (not hot) cam, appropriate valve springs, 23psi fuel pressure (TPI fuel pump at least), free flowing cold air cleaner, decent tuned EBL flash, 46mm bored 3704 intake manifold (a carb intake with adapter plate will work too), 46mm TB, calibrate the governor to shift at around 4700 rpm and 3.23 gears. You may get away with the stock intake manifold, stock TB and stock calibrated governor (around 4400-4500rpm).
With a VRFPR and the tuned EBL, fuel efficiency and emissions will meet LO3 stock standards.

 

Cam, exhaust and tune.

 

No need to swap to the TPI heads. Your current heads, though crap in stock form, flow slightly less on the intake side and but better on the exhaust side, than the TPI heads. I would recommend having the stock heads ported as much as possible. You should see nice gains there.

The LT1 cam is a popular choice for cam swaps. A bit too mild for me personally, but anything is better than whats in it now. Just remember that you'll need to freshen up the valvetrain as well. This includes valve springs, rocker arms, and pushrods. The 1.6 rocker arms are a good idea. You'll see gains there as well, even on a stock setup. Definitely go full roller or at least roller tip if you can afford it.

There are several options are far as intakes go. Holley, Edelbrock, and GMPP among others, make aftermarket TBI intakes for our cars. These dont require an adapter, which helps because hood clearance can be an issue. Your other option is to run a carb intake with an adapter like you mentioned.

I would recommend the underdrive pulleys. I bought the March Power and Amp 3-pulley set up and noticed slighly better throttle response and top end. Its a good bang for your buck... DEFINITELY get a set of headers. The stock exhaust manifolds are extremely restrictive. Pair that with a 3" catback and your car will really wake up... As far as upgrading the fuel pump goes, the TPI fuel pump is a good idea. But im not sure what the limits are of the stock fuel pump and when exactly it becomes necessary to upgrade.

Also check the stickies at the top of the forum and use the search. These will answer a lot of the questions you have.

 

What about some trickflow heads ? Yeah they are expensive but if i make the effort i can buy one and then the other one, and no im not gonna put one then the other on lol. But anyways i have heard good things about porting the swirl heads , so ill prolly do that since they are already in the car.

About intakes im thinking on getting a carb intake and adapter , i have heard that the performer tbi is not much diff than stock one so carb with adapter seems a better option.

So a lt1 cam with a 1.6 roller rockers should give me some noticeable changes. and yah im deff getting the underdrive pulley kit when i can.

First ima do a full exhaust system with 3 inch from headers back, i talked to a local muffler shop and he charges me around 300 bucks for the complete system from y pipe down to a muffler with tips , headers not included but im deff gonna get a pair. And yah i should upgrade my rear end to something thats atleast posi i hate not having any traction i cant accelerate hard from a red light without making my one wheel drive firebird burn rubber

 

Cam $100
Intake $150-$200
TBI adapter for intake $50
1.6 rockers $100
Valve job for heads $300 with new stem seals
TPI pump $100
Heads $300? (NOT the trick flows)
Chip Tuning $??? You'll have to pay someone to tune, and wait and wait until it gets tuned in properly, or you'll have to buy the equipment ($200+) and learn to do it yourself (time).

Now - consider used complete 350 motor ....

I bought my 350 used for $600 off craigslist - that was carb to pan
$30 for a 350 TBI knock sensor
$50 for a TBI 350 chip - no tuning required since it's designed to run the 350 anyway.
$120 for 350 injectors.

Exhaust would be the same, and rear gears would remain the same.

I think you'd get a much better bang for the buck with a straight 350 swap. Just something to consider - a 350 TBI swap might be easier/cheaper/more power for the money.

The big seat of the pants feel is going to come from rear gears, regardless of motor.