I just got a 91 firebird 305 TBI. of course it is too slow for me and will need a lot of work without a lot of money. I see that there are some nice ways to modify the TBI system but I also have a 600 CFM edelbrock carb and a pre 87 style performer intake (I read it can easily be modded to fit this newer engine). how much work/ money will be involved in getting this TBI working real well? How much (if any) worse will the fuel millage be with the carb? If I switch to these parts without changing anything else (aircleaner too) what can I expect to gain hp/et wise?

Also how finicky is the computer control system on these cars? can I change just about everything without a worry or will I need chips/ expensive tuning.

Im thinking Carb is the way to go since I have everything except the fuel pressure regulator I would need.

Let me know your opinions and what kind of modifications are good if you can convince me to keep this set up.

Thanks

 

well youre probably going to hear different,but this is my opinion.go with the carb.the computers on our cars are somewhat forgiving,but to get any real power out of it requires extensive tuning,alot of it while your sitting in front of your computer,not in front of your engine.a carb is a whooole lot easier to tune.if you go with a carb,you can clean up your engine bay ALOT,getting rid of the majority of wires and sensors that are making a mess out of the engine bay.now there are pros to keeping the TBI,and im not totally against it.some of the pros being fuel economy,cold starting,and when there is a problem,you can usually tell what it is with the on board diagnostics.but then again,with a carb motor,there arent any sensors to go wrong,so thats something you wont have to worry about anyways.well i wuold write more but i have to get ready for work now.oh boy i cant wait to see all of the flames im gonna get.well as i said,its MY opinion.later ya'll.

 

let's see, a simple and reliable electronic system or a carb that will run like crap half the time. hmmmmm, thats a tough one
seriously, it is always cheaper and easier to work with what you already have on teh car. there is plenty of power out there on teh cheap.
just do a search through the topics for 13sec and 14sec formulas or do a search under my name and you will see how to run in the 13's for well under $2500with a 305 tbi(this formula includes all chassis as well as engine mods neede to run fast and consistant for that cheap)
you have a good platform for power with good mileage. if you strap on a carb you will sacrifice a lot of mileage, you will lose the computer control that can compensate for weather and give you peak performance all the time, and you will make it more difficult to pass emissions fi your state runs them.
for the $300 of your new carb + the 125 of you new intake you could do the ultimate tbi mods parts 1&2, a 160 t-stat, an open elemnent air filter, get a useed edelbrock performer tbi intake, and an LT1 cam with new valve springs. once you add the cam to the scenario you can see how much more power is available on the cheap witht he tbi(this formula woudl put you well over 200rwhp)
i am going a lot faster than almost anyone i know of that has swapped on a carb, most 350tpi guys, and some LT1 guys, all out of a 305 TBI. how many carbed 305's can say that? not many.

later
tim

 

14.2 w/ alluminum heads, better intake, throttle body, full exhaust, suspension, 4.10s, stall. I hope that is before the cam and you are well into the 13s now. Because that is not very convincing for me to stay tbi. Plus you must have missed the part about me having %80+ of all the parts I will need to do the swap. The main thing I will need is a fuel pressure regulator. I have everything else (that I can think of).

Sorry If I sound like im getting too defensive but that dosnt seem real impressive. but then again I havent had an f-body for more than 2 days. but carb seems easier/cheaper/faster to me.

Still looking for more opinions/ rebuttals.
Thanks
Danny

 

if you have a 305 the choice should be TPI or TBI. A carb won't do you much better than a TBI and you'll get wost milage. For a 305 I think a TPI is great if you can find a complete setup to swap. On 350s TPI seem to restrict the top end too much. And if you have a 350 or bigger a single plane carb intake and a bigger TBI is an awesome bang for the buck.

 

actually that et was on a blown posi with 3.54 gears, a stock chip and the stock cam.
my position on the carb vs fuelinjection thing is simple. if you look at racing on any level, if they allow any form of electronic fuel injection, the fastest guys all run it. fuel injection and electronic management allow for 100% control of fuel and timing, which is something that mechanical systems liek carbs and mechanical distributers can't say.
it is the accuracy of hte control that makes power, not just having more gas or air.

lateer
tim

 

sounds a little better now. did you have the heads/cam/ intake at the time? what was your 60'. Thanks for your opinion though it is helping, just need more info.

 

Carb = works...eh right now

TBI = works great with a little effort.

Think of a carb as a toilet on top of an engine.

Think of TBI as a fine tuned, electron pumping, fuel metering, stoichiometric instrument.

 

i thought about doing the TBI>carb then i started reading up on the TBI and saw what i could do with it do i decided to stay with it...youll also need a new distrubutor to switch to carb...i decided definetly not to go carb after taking a 4 hour trip with a buddy of mine in his 78 vette...everytime we stopped for gas he went out there with his little screw driver and tried to tweak it alittle better...and we stopped at ALOT of gas stations lol

 

Thanks guys and keep em coming. hopefully wednesday I can get the tranny mount in it and take it to the track bone stock. Then ill play around with some induction stuff and get a shorter belt to ditch the smog. My plan right now is to get faster every time out. that shoulcnt be hard considering how slow it is right now. Wish I had some money to throw at it though. The mustang takes priority though since it is my car. ( another pair of rims, more tires and an intake on the way soon) I dont want to tie up my money in my girlfriends car so once it gets to the point when money has to get spent it prolly wont get much faster too quick.

 

how fast is your mustang? since the TBI is a 16 second or worse car then youll see improvements anytime you do something to it...now if it was a stock 14 or lower car thats when its hard to get improvements...do the ultimate TBI mods and stick a open element on there you will see a big difference

 

ive run 14.3 I will be in the 13s soon if not tomorrow (long shot).

yeah thats the plan. run it tomorrow then by next week put on a better aircleaner take this TB thing a part and play with it and delete the smog. Hollowing out the cat sometime soon too. Then it comes to spending money.