what can i do to my 91 fire bird as in mods and i also have a 84 firebird s/e that i just put headers and new exaust but it backfireswhat can i do or need to

 

First the 305 mods:
exhaust, exhaust, exhaust! The stock exhaust is very restictive and will yeild instant results in power gains. After that you'll need to get it sucking more air in, now that it can spit it out. A k&n filter or an open element/cold air setup is the best way to go. From there you can move onto a new intake manifold and maybe even a higher flowing TBI unit. There are many free TBI mods available at https://www.thirdgen.org/newdesign/tech/ under the Carbs/FI section.

The backfiring on your SE is probably from a bad O2 sensor, change that out and you should be on your way.

Good luck!

 

Check for exhaust leaks, my car had a collector leak for a while and when i let off the gas it would suck in cold air from the leak point and backfire.

As far as mods, I agree exhaust, open element filter, ultimate tbi mods (Free), get your timing around 8 degrees advanced, make your fuel pressure regulator adjustable (Free) w/ a fp gauge, gears & posi for big sotp, after all that then you can tackle some engine mods. LT1 cam 40-50 bucks, intake, headers, heads, and then move on to suspension and drivetrain so it can handle the power you've made.

 

thanks would any one know what kind of exuast and open end element to get . as in sizes thanks again

 

For exhaust you'll want to look for systems made for the TPI single cat cars. You want 3" exhaust all the way through. Catco 3" cats are good, any 3" catback, and headers with 1 5/8" primaries into a 3" Y pipe. As for open element any 14" x 3" air cleaner will work, you'll probably want to look for a flat base though so you can ditch the spacer ring on there.

 

ok i looked in jegs for the air cleaner but it has many 14" k&n does any one know the exact one a ID # would help i just want to make sure i get the right one u know

 

I couldnt find a 14x3" KN element and I looked every damn place, so I just got a holley oil element, its all the same ****. Actually using KN oil with it lol

 

I would like to recommend changing the gears and adding posi to the rear before going into the motor with a cam or anything of that nature. I wouldn't replace the intake until I was ready to do the cam. Only need to go through that torture once.

 

Hey,.... I bought a 3"x14" 360 chrome air cleaner from AUTO ZONE for $ 20... The K&N 3"x14" air filter was only $ 45 .. It was about a year ago, so I'm trying to remember what # the filter was... I used the information from a vehicle with a stock 14x3 inch air filter and AUTO ZONE had one in stock.. on the shelf ... I think it was an 80's cadilac with a 350 deisel...
Sorry I cant be more specific... but I know they are out there

 

You can buy an Edelbrock open element...14" x 3"......#4207...........this is a drop-base though, so you will need to keep your TB spacer, and spin your coil around and bend the bracket a bit so your new air cleaner doesnt rub wires and cause a short. You can use the tech section to tell you more. This part goes for around $65 give or take.

-blain

EDIT: As for any car you buy/find/steal/received as a gift...do a tune-up.

(1) Replace the spark module
(2) Replace the spark wires (I recommend MSD Superconductor 8.5mm wires...cut-to-fit)
(3) Replace spark plugs, and ensure gapping is correct...while doing so, punch 8 holes in some cardboard and label each hole 1-8. When you pull the plugs, insert each plug in its corresponding hole in the cardboard. (i.e. cylinder 1 plug goes in hole #1 and so forth. Using a Haynes manual (the only good of this manual is the color photo of spark plug wear)...for all else USE A CHILTON. If you have a friend with some mechanical knowledge, check compression on each cylinder using a compression gauge (roughly $40 at any parts store) and ensure that there is less than a 15% difference between the two cylinders with the least and most compression.
(4) Check the cap for any cracks or discoloration, replace as necessary.
(5) Replace coil
(6) If you are feeling really froggy, drop the money for a code scanner, I dont remember if you need an a-b scanner or OBD. when you find out, use it, and decipher your codes.
(7) Change oil and filter, and perhaps fuel filter also.

Some may think this is too thorough, but you will learn alot about your car during this procedure, and will find most of the problems your car may or may not have at this time.

Good Luck