ok..im a learn as u go pontiac owner...1968 firebird....400ci....it needs a new carb.....just need some advice on what brand and what cfm suggestions you may have. i want this car to RUMBLE. ..dont wanna race and dont need to go 120mph...just wanna get to 60 real fast....just alot of initial torque (throttle response)   any suggestions welcome....thnx  

If you aren't changing manifolds, you are pretty well stuck with the Q-jet and there's nothing wrong with that. There are several good carb shops listed in HPP that can do a full rebuild and resto on your Q-jet and make it outperform many aftermarket carbs.
If you are changing to an aftermarket aluminum manifold, you can choose from the excellent 600-750cfm Edelbrocks or the tried and true Holley 600-750 vacuum secondary carbs, depending on your other engine and driveline mods. Check out their websites for advice on how to pick one for your setup. Remember, too little is better than too much and vacuum or air-valve secondaries are better than mechanical (double-pumper) for the street.  

b-formula....ive only owned the car for a month...just stumbled across it...had to have it..been in storage  for years (1999)...i have no idea whats inside the engine, but it does have a edelbrock  torquer intake. it had a crapped out ignition system, so i converted it to HEI.New distributor, wires and plugs. Motor runs strong on jack stands but carb is a pile of bent linkage and leaks.... rather than try to rebuild (being ive never rebuilt one) i'd rather install a new one. my bird has a 400 turbo tranny  that i finally got the linkage and shifter for . I  installed it and the tires turn in all 4 gears on the jack stands.I cant drive it ...haven't gotten to the brakes yet !! anyway..it has a holley carb on it right now that looks like someone adjusted it with a sledge hammer. i think i wanna go with the holley 750, ...acording to holleys formula 400 x 6000 rpm / 3456 = 694.   is that too much? should i go with a 650 ? why the vacuum secondaries, i always liked the mechanicals, are vacuum secondaries better , more reliable ?

            thanks WOLF68


ps. i know the engine and tranny are not originals...i think engine is an early 70's. How do i figure out what gear ratios are in the rear end?  

My wife's mother had a new 67 Bonneville convertible with a 400. It was one with a factory AFB. 67's had either the Q-jet or AFB. Those were only 500 CFM. That old heavy boat would rip the tires up and still got over 20 mpg. I have given up on Holleys and have had good luck with Edelbrocks. The 600 should be fine for your combo and you can find them factory rebuilt on Ebay.    

I had a Carter 625 AFB / Edelbrock Performer intake on my 406, Hooker 1 5/8” headers and a 3.08 gear in my ’72 Firebird when it was my daily driver, and I would get 14/18 mpg driving it with a light foot.

It was only after I installed larger sway bars, stiffer springs, a disc brake rear end, and wider wheels with lower profile rubber did I notice the AFB starving for fuel in hard turns- a weakness of any carb with side- mounted fuel bowls. I went to a Holley 750 w/ vac. secs. and I could now powerslide through the turns at will. My mileage dropped a few mpg, but the car was alot faster with just that carb upgrade.

Geno  

Holley makes several spreadbore carbs.  I have an 800 cfm double pumper on my 1978 462 ci TA and have not had any trouble.  If you use a Quadrajet you may have a problem with fuel starvation.  My car would die under hard acceleration in 2nd gear because the fuel bowl in a Quadrajet couldn't supply the motor.  

ok, ive decided on the edelbrock thunder series....because everyone ive talked to seems to prefer the edelbrock over the holley. but now do i go with the 650 or the 800 ? im just guessing, but i think the car probably has a fairly radical cam. it has the torker intake , and headers and a holley carb. so im guessing  the engine will handle the 800.........correct me if im wrong  

It would be a real help if you could find out which cam is installed. Also does it have stock rods in it. You mentioned earlier about the 6000 RPM range to size the carb. If this thing has stock rods in it I hope you also have a good catcher's mitt. Chances are you won't see much over 5000 without problems.
The 400 core motor I bought for my project had Q-Jet with 805 CFM. It was on one the more restrictive intakes and looked to be set up for the secondaries to not open much more than half way. The 650 should give you great low end, if the manifold doesn't kill it, and should be fine up to about 5000. The thunder series is set up for richer conditions with bigger air bleeders. Too bad you don't know someone that has one you could play with to see if it will work for this combo. Try to talk to the guys at the track or local club in your area to what their experience has been. Even non Pontiac clubs will be of help just stay away from the Blue Oval guys they don't want to get beat up by some Pontiac guy.
Good Luck  

To answer your earlier questions, first off the reason I recommend a vacuum secondary carb is because of their design they will only flow what the engine needs for its rpm and load range. It's hard to over-carb with a vacuum sec. carb so you could get away with a 750cfm, but a smaller carb will be more responsive. The last post makes a good point about your max rpm, were not dealing with a small block Chevy here!
Your other question is about gear ratio, if you want to get dirty (and changing the gear oil and posi additive is a good idea), pull the rear cover and rotate the ring gear untill you see some numbers on the side of it (ie: 11 41) divide the larger number by the smaller number to get the ratio. Or simply jack up both rear wheels (use stands), mark both tires and the driveshaft, with trans in neutral, rotate tires (both the same direction) for one full turn and count the number of turns of the driveshaft. 3 turns and a "little bit" is about 3.08, 3 and a half = 3.55, not quite 3 and a half =3.42 and so on, this will give you a close idea.  

ok fellas...right or wrong..im gonna try the 650cfm edelbrock thunder series.  advance auto parts tol me i could try it, and if it didnt work the way i liked, they would take it in exchange for another  if i brought it back within a few days and claimed it to be "defective".......that sounds good to me


   thanks for all ya'lls input, it was very helpful !!!! and i'll give a report asap

           WOLF68  

Probably a good choice and with an offer like that, who could refuse?