depens if its bone stock yer in good shape but if you have head work and or a big cam the car is trying to breath better so a bigger carb will let it but not to big tryed a 1250 domminator with all the trimmins on a 383 small block nova and it would just dump gas out the headers (this was just a way to show a friend a little over kill cuz he had a simmilar question
The very best carb for the car came on the car. Have the Q-Jet rebuilt by a competent Q-Jet man, and you will never need another carb. Ignore the hype about "Quadra-Junk" and "Quadra-Flood". Those are sour grapes fom people trying to do something they simply don't understand.
Cliff's Q-Jets in Ohio can modify tht 800 Q-Jet to support well over 500 horsepower. Q-Jets have the unique design of the tiny primaries and huge secondaries. This makes for good response at low engine speed, and plenty of volume for high-end. Carter imitated it with ThermoQuad.
Most prosfessional carb guys report significant tuning issues with the E-clones of the Carter carbs. The E-Q-Jet, however, has shown to be versitile and effective. Price is HIGH...
If you're dead-set against Q-Jet (for whatever reason), Holley is the only good alternative. The 3310 would be first choice, but an adapter is required, and adapters are not recommended.
BTW, 600 CFM isn't nearly enough for a 400 Pontiac. 750, minimum, unless you're using small valve heads, and trying to make all your power under 4,500. (Don't laugh, I have customers with 400s in pickups, and that's EXACTLY what they want)
Check out Jim Hand's book "How to Build Max-performance Pontiac V8s" by SA Designs. You will find tons of good and CURRENT information on carbs and cams, intakes and headers, without all the mythology and superstition found at the hobby level today.
Also, check out
boyleworks.com (click on muscle cars)
classicalpontiac.com
performanceyears.com
These sites all have excellent Q&A sessions for Pontiac-specific inbformation (real Pontiac, not corporate Pontiac).
Go to boyleworks.com and click on muscle cars. Then, go to the restoration and performance forum. There's a recent post there from Jim Hand, that has a link to Cliff's Q-Jets. The title of the thread refers to the "book".
Opinions on Holley vs Edelbrock vs Q-Jet are just like GM vs Ford. Everyone has their own...
Having said that, I really like the Edelbrock 600 I'm currently running. It actually gained me about 1.5--2 mpg on the highway too. I've used Q-jets (and 4 jets, remember those?) in the past with good luck also, but didn't seem to perform for as long as my Ebrock. Holley fans, I guess I've always had lemons, owned two and not a big fan. I have friends who believe a Holley is the only carb made. Gotta love it.
Most overcarburate. If your 400 is stock, or near stock, 600 CFM is more than adequate.
I look up Cliffs Q-Jet and they really didnt have much to offer, but http://www.customrebuiltcarbs.com/ has a wide selection of carbs, including Q-Jets, they do rebuilds or even build you a custom carb, so take a look over there everyone.
The 600 is an economy carb and a pile IMHO. With your car being mostly stock and you wanting good milage, I concure with Mr Pbody. Cliff knows q-jets like no one else. I am a holley guy myself but dont expect good gas milage. The Q-jet has very small primaries which are great on the milage and when the secondaries open, bammmm big gas sucking secondaries. You can try your luck at Schucks but you may end up trying 3 or 4 to get one that works right!!!
Get a quadrajet that has been rebuilt by holley.They are pretty good unless they get exposed to dirty fuel.Where quadrajets may all look the same,they come in so many configurations that you have to be very specific when you pick them out.Too lean,you might burn up a piston.Too rich your just stinking up the place and fowling out plugs.A properly jetted Carter AFB competition carb mixes pretty well.And they dont loose adjustment like your holley designs have been caught doin.its like set it and leave it.They come with an automatic choke that is preset.Its easy to take it off and run a cable choke.
I got a reman Q jet a few years ago , The shaft fell off the side with the choke linkage . I like Edelbrock myself . Had two , rebuilt and rejetted one for a friend in an hour . Bout to buy a performer package kit for a 4.3 chevy. Rob
i got a '79 TA with a 400c.i. the 600cfm edelbrock lets it run but it is not near the amount of air that big block takes in so it whistles and cuts way back on power now i run a 750cfm A LOT MORE POWER. Although i am running a few mods
Ive noticed more than a couple posts on various threads about a "big block" 400...is there a big block and a small block or are people just saying "big" in that it is a rather latge small block engine? Just curious cause I always thought the 6.6 400 Pontiac was a small block engine.
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