Hi! New to this board and I think I could get some useful help here.

I've got the car as stated in the topic and I was about to do some maintenance to it. Until I figured as I'm picking it apart anyway I could use this time to up it somewhat from 190hp to something more.
I'm also interested in a more brutal sound to it than I have now.
I've spent practically the entire week obsessing, researching and calculating the costs. But before I make any unnecessery and expensive purchases I figured I'll just ask someone who knows this stuff better than me, you guys.

I've already looked up the option of changing car to something with a 350, but I like my car. I won't swap engine as I don't have the tools or time, it would also be to expensive.

I know the formula has somewhat higher performance than the standard car but I don't really know what makes that power, the TPI?
My budget would be about 1200-1500$.
I use it as an everyday car but the MPG isn't really an issue.
Optimally I'd land around 300hp with bolt ons, but perhaps that's to optimistic on this budget?


Headers:
So from my own research I've found out that headers is a must. From what I can tell there's a huge difference in price between 1 5/8 and 1 3/4. I was thinking of 1 3/4, but that's 450$ right there, will it a big difference between them performance wise?
I'll have to change the entire exhaust system probably, I'm counting on it.

Camshaft:
Secondly I've been looking at camshafts. I'm confident I can install it but I'm not entirely sure what to get. Same things go with rockers etc.

Heads:
New heads. I've been pacing back and forth between new heads or a new camshaft, I figure they're both beneficial in their own way. I figure heads would be the better of the two performance-wise. But new heads are also more expensive than a new cam. I'm also not sure if the heads on the formula are good enough from the start. Any thoughts and recommendations?

Ignition:
Have no clue if this will help anything at all. Are iridium spark plugs worth it? Will I see any benefit from changing this?

TPI and computer:
I won't change the TPI, It should be adequate to my goal.
The computer I know nothing about and I haven't looked in to it at all.

Grateful for any and all suggestions!

 

300hp on a 305 with $1500 is very optimistic. You can chew that away with just good exhaust components. My suggestion is start there.


Yes, full exhaust is a must. On a 305 1-5/8 are ok. I'm running them on a 355 but 1-3/4 is better for both engines. Dyno Don's and old SLP's are the way to go. Keep doing the research you've been doing and you likely won't make any mistake as long as you don't get yourself in a rush.


Don't worry about camshaft for now, learn more and you'll be able to make a better decision. The factory camshaft on the lower output tpi is a bit weeny. The higher output tpi had a better cam but that there's a lot better options possible. Again, at this point there is much to learn and in the end you may not want to change it.


Unless you're going to pull a lot more money out, stick with the factory heads. As the engine sits now they're not a restriction. Maybe down the line if you do decide on heads, you could change cam at the same time. But by the time you do that you could have transplanted a 350 in and those mods will go a lot further.


Leave the ignition alone unless you need a tune up. You won't see anymore power from fancy aftermarket parts than you would from GOOD factory replacement parts. The ignition should be looked into if you start going more radical in power.


If you're staying with a 305 you can stay with the TPI and it'll be much less of a restriction. 350's they are a restriction out the box. More things to think about first. The computer as it sits will compensate for the exhaust changes. You can have someone burn you a PROM to better fit the modifications you make, learn how to tune yourself, change to EBL or megasquirt or FAST or whatever you want as you figure things out. Changing computers is a whole ball of wax to tackle right now. You'll be fine with the factory settings for the time being, but I'd suggest you talk to Tuned Performance on these boards for a better PROM.


Find out what gearing is in the axle. A 3.27 or numerically higher will feel like a huge HP gain if your factory is 2.73.


Good axle gearing and exhaust are great places to start for more performance. Keep learning and you'll figure it all out.

 

Exhaust is always job one on these cars like aliceempire said, above. Headers and matching y-pipe for sure- the factory stuff is super-restrictive. 1-5/8 is just fine. 1-3/4 works a little better in most cases but the difference isn't dramatic. If the cat isn't melted inside and the exhaust hasn't been replaced with a lousy crush-bent cheapie replacement setup after the factory one rotted off the car, you COULD keep using them, but really everything needs to be replaced right back to the tailpipes. It's all pretty restrictive.

Some free or nearly free stuff....

Tune up stuff, yes. Nothing special needed here. Just fresh and in good operating condition. Bump up the base timing from the stock 6* BTDC setting to 10* BTDC using the PROPER FACTORY SERVICE PROCEDURE for a little more power without any real downside (other than it won't like running on cheap gas any more). Air box "free mods". Remove at least the rear screen from the MAF. Make sure the TPS voltages are dead-on both at idle and WOT (the early style TPS has some adjustment in it and it's usually wrong from the factory). Clean out that throttle body real good while you're at it. You can also buy an extra MAT (Manifold Air Temp Sensor), mount it up in the air box and extend the factory wiring up to it from the stock sensor location in the underside of the intake plenum. It won't make the car any faster but it will make it more consistent from run-to-run, especially when hot.

Speaking of the air box, the factory air intake system on a Firebird isn't as good as the factory one on a Camaro. An aftermarket cold air intake will do better than the factory piece, but expect no miracles. I used the SLP one back in the day and it was a NICE setup. There are probably millions of them available now from cheap to pricey. Look for quality and decent size piping would be my only suggestions.

Speaking of hot... TPIs with their LONG metal runners HATE HEAT. It's their nemesis. 160* thermostat is what I always run in a TPI. And either a lower temp fan turn-on switch to match, or just a manual switch you rig up to ground the relay activation wires so you can kick them on any time you want (see tech article on this board about the fans). At the dragstrip, a big bag of ice to plop on top of the plenum between runs to cool it off. False rumors department: NO, a 160* stat won't throw a check engine code, NO, it won't run the engine so cold it causes accelerated engine wear and NO, it won't prevent the ECM from going into closed-loop when you're driving around on the street. If you heard any of that crap, forget it because it's not true.

Moving on....

Forget changing anything internal to the little 305 because it's wasted money. With one exception... possibly the camshaft. If it's a factory 305 Automatic car, the cam in that motor is what we call around here the "peanut cam". It's specs are small by tiny. Anything past 4000 RPMs and its wheezing pretty bad. It's just an absolutely awful camshaft for sporting intentions.

Upgrade possibilities for the cam: A factory L98 (350 TPI cam) or a cam from a later factory LT1 engine (nearly identical to the L98 cam but with a little more lift) is an obvious upgrade path and those cams can be had for cheap as people take them out of factory motors. It's a factory roller cam, just like you have now, so you can reuse your existing lifters and roller cam gear if they're in good shape. You don't even have to change the valve springs if you don't plan on spinning past ~5500 RPMs. Put in a new timing chain when you replace the cam because yours is almost certainly shot by now anyway.

Custom tune for the chip in the ECM: Not needed until you upgrade the cam. Definitely recommended if you do upgrade the cam. There's quite a bit of power left on the table by the factory in the tune and as soon as you change the engine's basic breathing characteristics, that tune gets nothing but worse. Will the factory tune run the motor after you do a mild cam upgrade? Absolutely. Will it be anywhere near optimal? No. Work with somebody who knows what they're doing with those older OBD1 systems. They're a different (but simpler) animal than later OBDII system with flash memory. No, you can't just swap in bigger injectors and solve a tuning problem.

The good news is these motors do respond to most mods. Everything you do to them makes them a little bit faster so it's kind of fun to chart your progress and it will hold your interest for a good long while. When you get tired of it, larger cubes, better heads, better intake design and forced induction (or nitrous) await. They're probably second only to the 80s-era 5.0 Mustang in terms of availability of hotrod parts.

 

Alright. I've decided to do the mods on 3 separate occasions with three separate budgets. I
- Exhaust.
- Combustion.
- Fuel/air intake.

My reasoning would be as the exhaust is the biggest problem on stock, as well as the main course of action to make it sound better.
I'm thinking of getting the somewhat more expensive 1 3/4 headers, even with no dramatic difference, I won't think I cheaped out and I could reuse them IF I decide to up to the 350 engine, and still not have to think "what if".

When I do the combustion, probably later this summer, I'll look into a better cam. Thanks to aliceempire's advice I'll probably only look at new heads if I can find good, cheap, used ones.

Next year I'd look into fuel and air. I understand that the original air intake isn't as good as aftermarket ones, but unless I change the heads this shouldn't even be an issue? I'll let the TPI be on this engine.
I'll be looking at the PROM at this time aswell but probably spend some money changing it into something with a flash memory, perhaps not worth performance wise but just because I find it interesting.

Thanks for the advice!