Q-Jet, with proper tuning, you can get beautiful millage with that spreadbore... and those secondarys aren't too bad in the performance end either!
Ford installed Rochester Q-Jets on the 429CJ in the 71 Torino. They did it because of throttle response and impending emissions concerns. The 429CJ made about 370hp at 5400rpm but cranked out a reputed 450lb-ft of torque at 3400rpm. I don't remember for sure but I'm pretty sure that the Ford Q-Jet was a one-off though made just for the 429CJ. I actually used to be a Ford guy when I was a kid... ou:
I have always used Holleys. I have to admit though. I have never given the others a fair chance. Over the years I have a bought a book on Carters and a book on Quadrajets and never put them to use and the reason why is pretty simple. Whenever I had a car to fix with a problematic Carter or Quadrajets, I could just put a Holley on it to fix it. Not because that was the only way, but because I knew Holleys inside and out from racing. If I ever have a problem with a Holley, I can go right to it. When you know something that well, it is kind of hard to get yourself to fool around with anything else. As for horsepower, I can tell you from experience on the track and the dyno, the carburetor can make a very large difference. While these modern Holleys and racing brand version of them are more consistent, back in the day we could see as much as 30HP difference between two identical Holley 850 cfm 4781 DPs that were new out of the box. And, every once in a while you would get one that would just outperform the others. Those were usually kept as dyno room backup carbs. I personally had a few over the years that I guarded closely because they were just exceptional. I have yet to see any carburetor that would make more horsepower than a good working Holley. I have heard stories from some very credible people that those Predator box carburetors were faster, but they are so big and ridiculous that I never gave them a try.
I really like my Holley HP 950. It spent it's life on the dyno until last year. Now it lives happily on my Century.
I like the Q-jet for reliability and running and the AFB for ease of maintenance. The Q-jet is an incredible improvement over the older Rochester 4GC, which seems to be my nemesis, - I just can't get one of them to run right. Holleys? Yeah, I had one on a 390 Ford once, couldn't keep it idling. It needed tweaking everytime the weather changed or the sun went down. Rebuilt it 3 times and never got it right. I had an easier time tuning a set of Solexes on an old Mercedes than with that damn thing. I just put the proper Q-Jet on my Electra and the thing purrs like a kitten. The Edelbrock knock-off never did it for me either; - I found them more conducive to a SBC than a Buick. So I'm going to stick with the Q-Jet; - it's an incredibly versatile carb, GM used them on almost everything, and they ran very well. But, all that being said, if you're one of the few guys who can actually tune a Holley out and make it reliable, nothing beats them for high RPM punch. So what do you want to do, race, or cruise?
i am going to chime in again 4 years later. i had a king demon on my 555 bbc and it was terrible. had a bad main body that when they drilled + tapped for the fuel bowl screws the tap broke through the body and fuel would wick down the threads and into the engine overnight. i sent it bact to bg twice and got back worse ones, horrible quality control. i then ordered a pro systems dominator and have been absolutely thrilled with it. on the dyno it was fine right out of the box, i highly recommend them and patrick there is a great guy and he is reachable on weekends on his cell phone for tech assist, barry grant won't do that.
On a 70 Stage 1 462 I had a Holley 950 HP - loved the carb. I was/am putting the car back to stock (kinda) - went with an 870 Holley Street Avenger - electric choke and vac secondariers - it was a terrible decision. It runs rich one time, lean the next - fast idle won't k ick off, etc, etc. I have an old 850 dp that I am going to rebuild and put back on the car..... I have an 850 demon on a 69 firebird 455 car and have had zero issues - on a 71 Challenger RT 440 Mag car, I have a 800 edlebrock - again zero issues - Loved the 950 - hate the 870..............buickstaged
QF/Dominator QF had excellent response and hp. I recomend these for hot street strip enthusiast. Each Mfr and type has its Pros & Cons and I used most of them. Q jet, TQ, different holleys. Not Predator though For All out, I still like a properly set up the dominator. Tom
Larry, if Greg Gessler wanted max performance he would've went with Pro Systems Carburetor. Many of top builders in the nation has challenaged them and lost their bets badly to them. They make carburetors that would scare you and many others, their has been time differents as much as 1/2 to one second in quarter mile and 1/8 mile. they also make carburetors to suit your application if you decide to street and strip. Greg was not shooting for max performance at that time. look at Fred Katlin's 9 second car, there was no Quadra-Jet on there. it was a Holley, why because Kenne-Bell and Fred Tested all kinds of carburetors then and found out which was best for that engine. I have yet seen a company come close to Pro-Systems. If you think I'm B.S.'in you, look at the ProStock NHRA class they all have Pro-System carburetors, why I ask? I prefer Pro-Systems Carburetors for a reason, Tested and tried to be thee best.
Anyone who likes a Qjet would love a Thermoquad. They must have taken a look at a Qjets and said; where can we improve it. Better in every area that the Qjet falls short such as: two bowls with floats hung at the rear, cooler running fuel, no well plugs to leak, up to 1000 cfm, etc.. I have some great running Qjets and my race cars love the 1050 Dominator but all around for street and strip the TQ is my favorite. 925 TQ on ported/equalized B4B with 1/2 in spacer....smooth at ALL speeds. I used to drive all over the place with that setup. 10.50s. My Dominator on the same setup is OK but a pig on the street even with mods.
My friend once put a Holley 850 DP on his 64-1/2 Mustang with a 302. Cranked it over a few times and *BOOM* ...blew out both his mufflers. There was a nice fist-sized hole blown thru the bottom of each. I'm happy with the Q-jet.
...and, interestingly, every TQ (OK, two) I've ever had worked like a POS, and I couldn't rebuild them to make them work, either. And I used to be a mechanic, rebuilding whatever came my way. Maybe if I bought a brand new one. I dunno. I'm not picking on you, really, yours is just the latest post for a TQ. Now, I've had good luck with many other carbs, but most of that experience is 20+ years old, when gas and carbs and cars were really different animals. As far as I can tell, an E-brock is the same thing as an old Carter AFB, internally (well, OK, the idle adjustment screw is in a really different place, for example). I NEVER had the problems with an old AFB that I get with the E-brocks. I suspect that modern fuels have a lot to do with it. I haven't tried any science projects with the new E-brocks, just tune until I get reasonable performance...which has taken some time, as I only have set-of-the-pants calibration, now that I don't have a scope and readily available mixture measurement equipment.
The flat o-rings in the TQ are a common pitfall. If you don't replace them or get a good seal there it will run like crap. Also, the two floats need to be adjusted carefully and not be heavy/gas logged.
Do you have radical cam? High Compression? If not a Q-jet will do fine, if you do not want a Q-jet, a Holley 850DP will do the job nicely.
