Carburetor recommendations
 

I'm going to replace my carb soon and was wondering what I should get for cfm. Its a 350 2bbl soon to be a 4bbl.

Get a QJ for the year of your car.Tom

Second.

I've tried that route, cores I have found are junk or over priced. I'm looking into an Edelbroc AVS2.

Contact Sean at SMI and get a price for a done QJ for your application.Tom

If it’s not a restoration why pay big money for an inferior early Q-jet?

Plenty of reasonably priced ‘77 and later Q-jet cores are out there and are a far better design.

This. Get a new carb... it's new and works.

What would the recommended CFM for a 350 be? 500 or 650?

Cliff had been giving his approval, to quadrJet power, in Houston. I'd gat a 77 and up unit from them, as ;art mentioned, get it with an alactric choke!!!

The late ‘70s 350 smogger engines were all equipped with 800 cfm Q-jets.

Hard to go wrong with a late model 800 cfm core that’s been redone by an expert.

The avs2 carbs get rave reviews, I would like to hear back if you try one.

X2 on Quadrajet power… Can’t go wrong

Brent Flynn is still rebuilding QJets and recently did one for me.

There is no "best" carburetor for all applications.

If you want best driveability, fuel economy, power, and reliability; then the Q-Jet, as mentioned by many in this thread, is the way to go.

If you want lots of "wow" from the 16-year-olds at the local car show; then go with the shiny new imitation.

Jon

"If it’s not a restoration why pay big money for an inferior early Q-jet?

Plenty of reasonably priced ‘77 and later Q-jet cores are out there and are a far better design."

+2, 3 and 4.

Since I have no dog an anyones fight (retired from carb building) I'd stay as far away as humanly possible from a Holley Street Avenger (or any of their "bottom of the barrel offerings") and even further away from an Edelbrock AFB or AVS clone. The only good sound any of those make is when I "tink" them off the dumster outside the shop or hit the round trash can by the shipping table with one of my famous "hook shots".

I get locals crawling up here ALL the time with that junk on their "fresh" engine builds BITCHING about all sorts of issues. Then I take a look at the "cobbled" up install where they cut the original fuel line with a hack saw and ran 3' of black rubber hose around to the back of the carb for a fuel supply, often out over the valve cover so it can pick up heat from the exhaust along the way and rub on just about everything it between....LOVELY!

I love stories so here's a good one. Local guy shows up with his engine builder and they can't get their brand new out of the box Edelbrock AVS to do anything right. He is "dead heading" it with a Holley mechanical pump and a regulator and it starts "loading up" after sitting at idle for about 1-2 minutes. I removed it from the engine, put it on my test engine (with a return) and cranked the fuel pressure up to 10, then to 12 psi and it idles fine and doesn't load up or flood at all. Put it back on his dead-headed set-up and clear down to 3psi with the regulator and it floods out. How are you going to fix that? I asked him. He said it didn't do that with the stock mechanical pump but he got a bloody nose when the car nosed over top of first gear because the stock pump wouldn't feed it (454 about 430hp).

He also noted that aside from flooding after it sits at idle for a minute or so that fuel economy is HORRIBLE, and it's got a stumble going into the secondaries that will NOT tune out no matter how tight they wind the spring on the top flap. I ran into the exact same scenario when I drag strip tested them. I was finally able to get rid of the huge stumble by winding the piss out of the spring, but never completey got rid of the noticable transition onto the secondaries. We ran it on two different vehicles on that private track outing and it was the SLOWEST of all 8 carbs we carried along that day, on both vehicles.

I know, I know, go to a car show with 250 cars present and 238 of them will have an Edlebrock intake topped with one of those pieces of bovine excrement, or even worse a Holley Street Avenger.......because they are shiny and cheap.........FWIW.......

A Q-jet will provide the best combination of fuel economy, power and driveability. The triple venturi cluster design on the primary side gives sophisticated fuel delivery that rivals fuel injection when working right. Everything will fit and look right on your Pontiac with this set-up. The Edelbrock knock-offs will run of course, but will require a bunch of "rigging" and "hacking" to make it fit and operate correctly. Fuel mileage will never come close to a Q-jet. They are shiny though, won't dispute that. BTW, tuning parts for the Ederlbrock carbs are VERY expensive and hard to get. Just went through tuning a pair of AFB's and had well over $200.00 in jets and metering rods by the time I had a decent tune on them.

A continuation of my previous post (dog-gone telephone):

Obviously your car, and your choice.

However, the Q-Jet is a "spread-bore" carburetor.

I think the imitation is a "square-bore" carburetor.

USE THE INTAKE DESIGNED SPECIFICALLY FOR THE CARBURETOR OF YOUR CHOICE.

Do NOT just buy the wrong intake, and ATTEMPT to then install the carburetor with an adapter plate and mis-matched mounting gaskets; or your next post might be "I cannot get the idle down to a reasonable RPM" (read as vacuum leak from carb to adapter to intake)!

Take a look at the second line in my signature block (it also applies to intakes).

Jon.

i have a street avenger 770 that i bought a year or two ago, runs great out of the box. just adjusted idle screws and choke.

Cliff - tell us how you really feel ;) :D

How about "equus ferus caballus excretement"?

Jon

No use for the later Holley Offerings. I still buy the older ZINC Holleys at swap meets and have them dichromated after proper prep.
At least there, you can make sure the carbs are not damaged in shipping, (the latest 421 SD intake manifolds had excellent shipping boxes).

Tom V.