Hey guys; I’ve been chipping away at juicing up a 1972 Olds Cutlass S with the original 2 bbl 350, and I’m ready to put a 4 bbl carb on it. Thing is, it’s been a good 25 years since I’ve shopped for a carburetor, and there are simply too many options now to make a simple choice. Do any of you Edelbrock guys have any solid recommendations? I’m looking for a model with an electric choke, and I feel like 650 CFM would meet my needs; maybe 750 CFM. I’m very comfortable tuning Edelbrocks, so if I need to change rods/jets/springs, that’s not an issue.

The long term plan for the rest of the package involves 2-1/4” or 2-1/2” dual exhaust, 2,500 stall converter ahead of a 200-4R, 9.5:1 or 10:1 compression, mild porting on factory heads, an appropriate cam, and an Edelbrock Performer RPM intake. I plan on making this car a highway cruiser, so economy is a priority, but I want to feel it when I put my foot in it.

Any suggestions based on your experiences is greatly appreciated!

 

Get a 7042250 Qjet set up by someone reputable like John Herald.

 

I second the 7042250 Quadrajet. I did this to mine and could never be happier with the results. A properly tuned Qjet is the way to go.

 

Go with the AVS2 800 cfm and tune accordingly. Honestly a Qjet will need some tweaking, idle circuits especially, if you upping compression and cam. I am running a 800 cfm 78 403 Qjet with a custom tune by Everyday Performance. The tune was OK, I tweaked it upon rebuild. What wasn't good was the sledgehammer taken to the side of the carb. Choke issues, a bunch of spacers and only sort of works.

 

Thanks for the tip… Does Mr. Herald have a website outside of Facebook?

 

I'm running a Quick Fuel 780cfm on my 350 roller cam motor - 9.5:1 CR and an Edelbrock RPM intake.

It's a great newer-tech alternative for really no more $$ than a rebuilt Qjet would ultimately cost and easy to set up.

 

How is a Holley carb that traces back to it's introduction in 1957 a "newer-tech alternative? And the E-brock is a Carter AFB that was also introduced in 1957. The Qjet is arguably the most advanced 4bbl ever produced. It has numerous features to improve driveabilty. This additional complexity is why people who lack the patience or skills to tune them will put them down. Yeah, if I were building a max performance race car, I would go with the Holley. Race cars (especially quarter milers) don't really care about part-throttle performance. For maximum flexibility and driveabilty in a street-driven car, the Qjet wins hands down.

 

With all due respect to John, he doesn’t “tune” them, nobody does, not even Cliff Ruggles They simply put them back to stock specifications, with maybe a minor change here or there(idle restriction mods and maybe a minor jet change).
NO ONE is guaranteed to get it right based on any combo other than fully stock.
Buy a wideband, whatever carb you buy, and tune it right.
Just this morning, I dyno’d a 455 for a guy, whose daughter bought him a knock off (chinese) Edelbrock carburetor from eBay. It was so lean at the start of the pull almost 18:1, that I had to abort the pull right away. And this build ultimately only made 363hp. It started missing at that same lean point, the untrained/unequipped person would’ve gone right away to the distributor/ignition. But it was 100% the carburetor. We upped it 7 jet sizes and the miss went away. Lesson learned, again.

 

Joe with all due respect. Put em both on a dyno, vary the load and rpm and see how the react. Then try to do the fix. In my experience a majority of the time it’s been much easier and faster to get what I want from a newer style Holley type carb than a Qjet, especially now with the more limited parts availability for Qjets.
The newer stuff has multiple changeable air bleeds, power valve circuits, multi stage metering blocks and so on. There are a few companies out there that continue to improve the breed.

 

He will want a Qjet with adjustable APT, later 800 cfm models not only have more cfm but better chokes, castings and float set up. Just increase the idle circuits from stock. I got mid 13's idle, high 14's to low 15's part throttle and high 12's WOT. I would have been 14's both at idle and part throttle and 11's WOT without a wide band as is. All 3 can be adjusted within minutes without pulling the carb apart.

 

all this is sooo wrong.

 

stay away from Chinese knock offs

 

since you are comfortable tuning the E brock..use it. Even if you weren’t, it’s is without a doubt the easiest carb to tune.

you already know why. Edelbrock has a very simple chart to use for tuning all the circuits. you can run as lean as you want for max mpg cruise and richer for wide open throttle.

I would get one of the new AVS2 650 or 800

 

Really? Wow that’s a revelation. I didn’t buy it, nor did I tell him to buy it, his daughter did.

 

but you to use it anyway.. not very smart and a waste of time.

true Ebrocks are fantastic carbs. in my opinion they are more tuneable than the Qjet by far and will make more power .

 

Yeah, the E-brock is MUCH more tuneable than a Qjet

 

thanks for backing me up. one mistake you have on the E brock secondary air valve,, they are adjustable. the weighted valve isn’t, that’s probably why you are mixed up. all air valves are adjustable. and, not like the goofy hidden screw on the Qjet.

another fantastic thing about the Ebrock is it’s easy to do four corner tuning, as in all 4 corners of the carb are infinitely adjustable because the primaries have their own individual spring, and the secondaries have removable jets, which the Qjet doesn’t.

the Qjet would need to use two different sec rods to stagger jet, like the primary, but the sec would still be mechanically controlled by the lift cam. not a good way to get the correct afr per bank

you need a lesson on how amazing the Ebrock is and what it’s capable of..you clearly don’t understand them

 

The E-brock Performer that most people use come with the weighted air valve that is not adjustable unless you start filing the weights. The newer versions do have an adjustment. As for "four corner jetting", please enlighten me as to the difference between running different R/L jets vs different R/L metering rods? All that matters to the carb is the orifice area. More to the point, the jets are fixed and there is no power system on the secondary side of the E-brock. The Qjet secondary system incorporates a power enrichment capability by raising the rods in response to mass airflow. And yes, those secondary air valves are moved by mass airflow, not vacuum, so in reality the Qjet incorporates a mechanical, analog MAF. Rather than using electronics, the tapers on the secondary metering rods control fuel flow in response to mass airflow. But what the heck do I know about carbs?

 

He was informed beforehand but decided to go ahead and run it anyway. He paid for the dyno time so…..
As mentioned, he got it from his daughter as a gift, so he wanted to make every effort to make it work. Its painfully obvious you don’t understand the humanitarian side of that.

 

Please don't buy an edelbrock carb. Way better out there. A good Qjet or a holley are way better carbs.

 

wrong. stick around and you’ll learn why.

 

first off he asked WHICH Edelbrock carb..I said the AVS , or the ABS2. they are not weighted secondary flaps.

the AVS are not newer, they’ve been out for decades. they are the true performance version.

what are you talking about when you say there is no power system on the secondary side of the Edelbrock?

the Ebrocks actually have boosters in the air stream of the secondaries just like the primaries have. The Qjet has two big brass tubes sticking out in the airstream in the secondaries where fuel spills out …it’s crude and poor at atomizing the fuel. they also have two tiny tip in holes that supply fuel just above the air flap because the big brass tubes are not sensitive enough to draw fuel as quick as a central booster booster

the Qjet has horrible fuel distribution when transitioning to the secondaries because the throttle blades angle is the same way as the primaries , directing the fuel mixture to the rear of the manifold plenum..once the throttle is wide open, it’s better.

The Ebrock secondary throttle plates open in the opposite direction of the primaries for much better centralized distribution .

the Ebrock can be plumbed for dual feeds. It has two needle/seats and floats with big outboard fuel bowls that don’t get heat soaked like the central tiny Qjet bowl.

 

Correct. One of the many band-aids GM put on these carbs over the years. A carb manufacturer in Daytona showed me multiple issues with the Qjet some years back.

 

All carbs have weak spots. One is other than the Edelbrock Qjets, newest Qjet is from 1990. The Carter AVS had plenty of issues when Chrysler used them on new cars. Edelbrock refined them a lot. We no longer see my car runs terrible. We ask what carb and it isn't automatically an Edelbrock Carter clone. We will probably see these Chinese knock off carbs replace them as the problem child, all of them, Qjet Holley and Carter clones. I have smooth transition from idle to WOT, talking the AEM AFR gauge but my carb is modified quite a bit. There is no magic bullet carb. They all need their weaknesses overcome and tuned to your motor.

 

The Qjet has multiple week spots…we all know that.

I haven’t found a single weak spot in the Edelbrock AVS style carbs. can you point one out? they are an absolute joy to tune, between rounds in the staging lanes or on the dyno.

 

Well, I ended up going with the Edelbrock AVS2 650 CFM w/electric choke paired with a Performer 2711 manifold. The conversion from the original 2 barrel carb was fairly painless; I was even able to use the original throttle cable bracket with a little modification. The factory cruise control actuator even hooked right back up and works great. I jetted it for the altitude here, set the floats, and it runs smoooooth now. I am very happy with the punch when I put my foot in it.

 

I'm too late to the game here but I was going to suggest the Holley Street Demon. Incorporates the best ideas from the Q-Jet and Thermoquad with a lot of tunability and support. Also has the correct geometry for your 200 4R.

 

you did the right thing by picking the AVS2. congratulations.
you’ll fall in love with it even more as you get to know it.

 

That's the same setup I put on my 67 (330 ci) last summer and am very happy with it.

 

All I can say from personal experience is that the QJet is just as responsive as any fuel injected car I've ever driven. The only time I've ever had a bog on acceleration was because the timing needed some adjusting and the idle mixture screws were set too lean. For regular street driving I've seen zero evidence the "fuel transfer" thing pointed out earlier is even a problem. I've also never had a problem getting parts for it. Quadrajet Power and other sites like it have everything.