Mongoose

My first official tech question on this site! A little background, my car (1990 Firebird Formula) was an LO3 TBI car until November 2006. I converted it to TPI and it's been running great. I finally got the itch again to start modifying it and bought a new set of SLP runners. After doing some further research it appears that I may have wasted my money on these for a 305. Many on other forums have stated that unless I do cam,heads and such that I'll see nothing and more than likely I'll loose low end performance (not that I had a tremendous amount to begin with). My car currently has 160K+ miles on it but still runs strong. I'm the original owner and have been overmeticulous in it's maintenance. I know the TBI heads are considered junk and the cam isn't much better, would it be unwise to do a head and cam swap on this engine? Would it be a better idea to sell off the runners and pocket the money until I decide to build/buy a new engine more suited for them? I've already got a project or two for the car in progress and thought these would be a simple bolt on and go a little quicker scenario. I've got enough parts in storage, I really don't need more right now.

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Mongoose-1990 Firebird Formula
TPI/700R4 with stuff from Accel,SLP,Edelbrock,K&N,MSD,TCI,Spohn,Tokico,Eibac h,Energy Suspension,GM,Flowmaster,SSM,TPIParts,Autometer,Gr ant,Alpine,Boston Acoustic,JL Audio,TA Performance,BFGoodrich,American Racing

FirebirdPhil

The 305 will require a LOT of money to be put into it in order to see good HP gains. Does the engine have 160k on it or the car itself?

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"What if I told you insane was working fifty hours a week in some office for fifty years at the end of which they tell you to piss off; ending up in some retirement village hoping to die before suffering the indignity of trying to make it to the toilet on time? Wouldn't you consider that to be insane?"
-Steve Buscemi as Garland Greene in Con Air

Mongoose

Car and engine both. I'm not looking for major hp gains, this is a street/play/show car so I'm just looking to improve street level performance (throttle response, low end while still being able to stay with interstate traffic) without having to do major overhaul type work. I'd been thinking of putting a set of 1.6 roller rockers in to get a little more out of the cam as well. Again, I've been told it's not worth the effort on a 305 which seems to be the norm from larger cube engine owners but there are several people out there with 305s that are pretty stout performers and I'm apparently not hearing from them. Needless to say it's frustrating. I'm not looking for 300hp at the rear wheels, I'd be tickled to death to reach the 230-240 mark that the TPI cars had when new considering I've been living at the 170 hp mark all this time. Is that too much to ask?

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Mongoose-1990 Firebird Formula
TPI/700R4 with stuff from Accel,SLP,Edelbrock,K&N,MSD,TCI,Spohn,Tokico,Eibac h,Energy Suspension,GM,Flowmaster,SSM,TPIParts,Autometer,Gr ant,Alpine,Boston Acoustic,JL Audio,TA Performance,BFGoodrich,American Racing

FirebirdPhil

305s

Read the 2nd reply, that gives you an idea of what a few mods will do.

I don't think with heads, cam, and runners you'd be able to hit the 230 mark, but you should break the 200 mark. I'm sure once 19Stroked89 gets to this thread he'll be able to give some really valuable advice to you.

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"What if I told you insane was working fifty hours a week in some office for fifty years at the end of which they tell you to piss off; ending up in some retirement village hoping to die before suffering the indignity of trying to make it to the toilet on time? Wouldn't you consider that to be insane?"
-Steve Buscemi as Garland Greene in Con Air

Mongoose

Well, I guess I'll be putting them up for sale here and a few other boards. I can put the money towards finishing the 3.27 9 bolt I've got waiting to be rebuilt, that would definitely perk the bird up a bit over the 2.77s in there now.

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Mongoose-1990 Firebird Formula
TPI/700R4 with stuff from Accel,SLP,Edelbrock,K&N,MSD,TCI,Spohn,Tokico,Eibac h,Energy Suspension,GM,Flowmaster,SSM,TPIParts,Autometer,Gr ant,Alpine,Boston Acoustic,JL Audio,TA Performance,BFGoodrich,American Racing

19Stroked89

Alot of the people saying 305`s arent worth the money are referring to someone trying to build alot of horsepower and torque because thats what most people are going for when they do cam or heads swaps. If your not looking for all out power, just wanting alittle more get up and go then you can achieve that with a few bolts ons. I agree that if your upgrading your runners you will need more airflow to match the increased fuel flow which is where the cam and heads come into play. I dont know that I would put a bigger cam and heads on an engine with that many miles on the bottom end. You will most likely be upping your compression ratio which may not be to good on worn out rings. I dont see anything wrong with putting better cam and heads on a 305 for alittle more get up and go but you may want to put some new bearings and rings in bottom end first or you can wait and drop a 350 in that bad boy.

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Mongoose

Now that's what I've been looking for, some positive input for the little 5.0. I tend to agree with you on the mileage issue, a buddy's dad has a few late model roller 305s and 350s sitting around and would possibly be willing to take care of the machine work for a modest fee. Looks like there's fire in this project again.
Just a bit off topic, how much harm would these runners do to the low end grunt of my car if I simply port match them to my plenum and base (the ports on these are out of shape and smaller than the OE tubes) and do some cleanup work on the plenum?

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Mongoose-1990 Firebird Formula
TPI/700R4 with stuff from Accel,SLP,Edelbrock,K&N,MSD,TCI,Spohn,Tokico,Eibac h,Energy Suspension,GM,Flowmaster,SSM,TPIParts,Autometer,Gr ant,Alpine,Boston Acoustic,JL Audio,TA Performance,BFGoodrich,American Racing

MarkuzLS1

As somebody who's played around with building a 305, I always advise people to go with an engine swap. You can make power with one, but you'll never make power like the bigger engines.

Going from a 2.73 -> 3.73 in the rear-end was the best thing that I ever did with my old Camaro.

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Mongoose

That's the thing, I'm not looking to make BIG power. I don't race this car, I just want a little more get up and go as 19Stroked89 said. I've had 3.73s in the 10 bolt that was in the car originally and grew to hate them. I've got another 9 bolt with 3.27 gears to put together that may get the car doing just what I want it to and there won't be a need for a head and cam swap/engine build but who knows.

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Mongoose-1990 Firebird Formula
TPI/700R4 with stuff from Accel,SLP,Edelbrock,K&N,MSD,TCI,Spohn,Tokico,Eibac h,Energy Suspension,GM,Flowmaster,SSM,TPIParts,Autometer,Gr ant,Alpine,Boston Acoustic,JL Audio,TA Performance,BFGoodrich,American Racing

strc09

I've got 'em and I love 'em...but my displacement is a bit more than 5-liters.