how much CFM does it flow?

im thinking about replacing the stock Q-jet with a holley 600CFM carb. dont know much about it, its a factory refurbished 600 CFM holley 4 barrel. thats about all i know about it. do you think swapping them would show me any gains?

it would be bolted to a edelbrock air gap intake manifold

 

Up to 750 depending upon the year. I think the smallest is 650.

 

so a 600CFM holley 4 barrel would be a step down and i would lose performance?

 

That's more a matter of opinion than anything else.
Some people will tell you to swap to the holley 'cuz it's a holley! And that the flow will be lower yes, but it'll match your engine so it'll work better.... (which is probably true...)

But i'm one of the people that think the Q-jet is superior, I like the spreadbore design, and it's kinda a diamond in the rough, most people ditch it to hang in the aftermarket gang, without even thinking about it being a good carb...

To directly answer your question, since you only have the 305, i'm assuming no major mods, chances are it'll still be big enough, and will probably perform well.... after being setup correctly.... is it worth the setup time on the holley if your Q-jet is setup right now? I'd say no, tune up your q-jet, but hey, what do I know, i'm still running a Q-jet...

 

yeah as of right now my 305 is stock, but once it warms up i have a cam, headers, and a new intake manifold im going to put on it so i will definitely have more flow than i wouldve stock..

and i coupld very possibly get my hands on a pair of L31 heads but i dont have my heart set on it. if i dont ill have the heads milled a bit to bump up the compression, that will increase the flow more..

my dad says that the Qjet is a good carb and they can be tuned to perform, i believe him but theres just something about keeping the stock carb on there that is kinda making me weary..

 

The qjet can be tuned to supply 500hp. Its vastly superior in a daily driver application.

 

yea, you don't get a shiny fancy looking carb, and that warm fuzzy feeling of owning a holley/edelbrock etc. And you don't get the sticker to put on your car...
but hey, stickers and show don't do it for me, and personally i'd rather have the feeling of beating a guy with all those "go fast goodies", who spent $3k on fancy parts, chrome etc, doesn't know how to tune his car, and then him ask me, and I tell him I have stock heads (ported), and a stock Q-jet, and watch him cringe...

 

I know some members will argue but you also won't have the constant tuning fiasco of the Holley if you keep the Q-jet. Holley owners are always changing something or tinkering with something. On the Q-jet you get the primary metering rods and jets dialed in, dial in the secondary side, make a few minor adjustments and you are good to go for 50,000 miles until the next rebuild.

 

Keep the jet, there are guys running in the 10's in super/stock using a jet. The driveability is better with a jet.
If you're gonna change either go for an AFB, which is a sort of install and forget carb, or a BG, especially if performance is an issue. But I like the jet, it's like a Holley only with better fuel mileage and no fuel leaks.

 

If the Holley is a vacuum secondary model, then I'd say don't bother. If you are changing carbs, the only one to consider would be a double pumper - and that's only because you have a manual tranny. You don't want to go much over 600 CFM on a mild 305, though, that's for sure.

For the typical street-primary driver, the q-jet is the best choice.

 

Another thing to consider. I assume it's a computer controlled carb, so if switching to something else you will need a different distributor also, and you'll be bypassing ECM. I would send yours out and have it redone when you do the work to your motor. The Carb Shop (somewhere in CA) has done a couple for me and have always worked great.