hello ihave a 68 firebird 350ci 2 barrel, st300 trans. Im looking into swaping out the ol intake and carb for a new 4 barrel setup...Im looking for better drivability and performance. Would there be a good increase in perfromace? or am i wasting money. Or should i just rebuild the old 2 barrel and get a new flowmaster exhaust.... My wife gave me $500 to spend on the bird.
A stock 67-72 4lb intake and q-jet carb with 2.5" dual exhaust would be a good upgrade. If no one here close to you has an intake, i have one let go for $60 plus shipping. Dont have any spare carbs right now.
Definitely go 4bbl...you won't be disappointed. And contrary to to what anyone may say, the #17 heads that you probably have on there now will flow just fine with the additional fuel/air.
If you do it right, you should be able to do both mods for $500.
You could probably have a competant local shop bend up a 2 1/4" exhaust for a couple hundred bucks. If you're running stock logs the 2 1/2" won't met up easily and in any case is overkill for a mild 350.
That leaves plenty of money for an iron intake, qjet, carb rebuild it, gaskets, and coolant. With the remaining money, replace the points, sparkplugs, wires, and retime the distributor to get 36 degrees at maximum advance.
As for the 4bbl intake, yes you'll improve driveability and performance.
All these mods will improve fuel economy if you keep your foot out of it (like that's ever going to happen after you're tasted the new-found power).
While I generally agree with the comments above, don't expect miracles with that 2-spd auto. Especially if you have something like 2.56 gears behind it. Your best bang for the buck might be a TH350 upgrade and better gears. The 2GV 2bbl is a good carb overall.
While I generally agree with the comments above, don't expect miracles with that 2-spd auto. Especially if you have something like 2.56 gears behind it. Your best bang for the buck might be a 2004R upgrade and better gears. The 2GV 2bbl is a good carb overall.
Fixed it. If you're going to upgrade transmissions, might as well take advantage of the deeper 2004R first gear and get the overdrive.
That's the truth. My first car was a 56 Chevy with the 235 straight six and 2 speed Powerglide. Nothing put on the engine (split manifold and dual exhaust, 4bbl carb, etc.) made up for the Powerglide. Having a deep first gear, like Mike said, would make a HUGE difference!
No way would i put in an overdrive w/o at least 3.73 or more gear. Unless you want to be able to go 200 mph...
With the 2004R and 2.56 gears, 4th would be useless below 70mph. But it would be ok at 70+. And the 2.75 first gear would help a lot out of the hole.
The 3.73 would be a fun combination, but I would not go any higher as you'll make the first gear ratio almost useless. Anywhere between 3.23 to 3.73 would be a fun driving combination while still improving fuel economy, and lessening engine wear.
Agree on 1st gear. Had a 700r4 w/3.42's in mine. Pretty much useless even w/them. Best over all range for power-n-cruise is 3.08-3.66 3.55 not bad with taller tires. Havent thrown tires in the mix, so figure we should...
BTY, still have the 700 w/2800 stall convtr, adapter plt-n-cable, etc. Just in case someones interested. Not cheap. Art Carr 500 plus hp build.
Hard to answer. The ST-300 1st gear is a pathetic 1.765. That's almost like the 2nd gear on other transmissions. But your top gear is still 1:1. So it all comes down to how much RPM you're willing to deal with on the highway. It really is a lousy trans in that respect.
BTW, no one says you have to throw the trans out if you're not using it. You can install a 2004R without resorting to cutting any virgin sheet metal. If you're willing to put on non-numbers matching components like a 4bbl setup, what difference does it make if the trans is correct? Swap it back when you sell (or include it in the sale) you can still call it numbers matching.
I dont know... Used to race with a ST300 trans. Most guys beat me out of the hole every time. But catch'm at 70 mph and shift fly'n past like they left me at starting line. It was a blast. Drove'm crazy!
