I have a hypothetical question, to get opinions. If you had a very nice 1966 Skylark GS, that already as a few "upgrades" such as a ST-400 transmission and front disc brake conversion, but the rest essentially stock or "correct" (this includes a nicely rebuilt original to the car AFB carb), would you consider converting it to an A9 quadrajet setup? My experience with quadrajets is they really outperform the AFBs by a real world "seat of the pants" feel. The advertised HP increase is 20 hp. And the 0-60 is said to improve by a full second! I am not a drag racer, but I like the freeway passing gear aspect potential. The reason I hesitate is the EXPENSE of rounding up the correct parts. It can easily run into the $1500 realm to include a professionally restored 1966 Q-jet. Even the intake manifolds are $400-$700. Then there are all the hoses, fittings, linkage, etc. I understand even the kickdown plunger switch is unique to the Q-jet. Or should I just be happy as is? (I am not interested in a 2-4bbl setup).
maybe 20 hp and 2 tenths in a 1/4mile but no way a second 0-60. with a 750 edelbrock and open air cleaner is worth 3 tenths in a 1/4 mile or about 25-30 hp
Why would you go for a 66' specific Quadrajet? The manifold would be your biggest expense. Later model QJ's are better than the 66' model for a lot of reasons.
Well, I am not gong to do it. But to even use a 1967 Q-jet requires a different choke. And using any other than a 1966 or 1967 would mean I would not have the proper linkage attachments for the stock kick down switch. I do my best to make such mods look like "factory" to the untrained eye. I do not want to make my car look like some hot rodder got a hold of it with yellow spark plug wires and MSD coils mounted to the firewall.
I did this very swap last year. I was sensitive to the same issues that you are. Specifically, having it look hacked up or not necessarily factory. I think I came pretty close. I was able to reuse my throttle arm. So, no issues there. The choke on my 2 barrel was a standard hot air GM choke, no different than the one on the Q-jet. I did opt for an electric choke, so I rewired that. The only real issue was the kickdown. My 62 had a Dynaflow kickdown which a little different from the ST400. But I was able to put a linkage together that worked great and looked like it belonged there. Since then I've converted to an ST400. I'm using a factory Buick kickdown on the later model Q-jet. Again, it looks like Buick did it.
In 1966 did they not make a Carter AFB bigger than 625 cfm? Is it the only reason they chose to use the 730 Q-jet on the A9 option or the 425 on the big Buicks with the 425? gsgtx, wouldn't a open air cleaner on a Q-jet be more?
yes it would about 10 horsepower. i was wonder if any one was paying attention and ask that, lol. any 750 cfm carb and better flowing air cleaner would all be the same i would think, but i have only tried a 750 edel and open air cleaner on different 401 engines.
Too funny., I almost didn't want to ask from embarrssment I swapped a few intakes and carbs on my 66 GS way back in the day. I probably had 5 carbs to choose from and only one was a legit and a true swap in. The one carb I drove for 8 or 9 years was a 500AFB which I mentioned here plenty that I only found out till the day I sold my car it wasn't a 625 AFB. I tried swapping jets back and forth for a 625 carb so that was a wash. The factory dual quad intake I used 2 600 AFB's that came as a kit for a dual quad offy intake. No low end and perked up a tiny bit after a 1/8 of a mile but still slow and also weren't correct. Tried a friends Holly 650 and it just bogged. This was over 35 years ago so my memory's are off. The factory "legit" carb swap was a 66 Q-jet carb and intake manifold that came off a 66 Riv. I thought the small primary's would give a nice crisp response but it didn't and it also didn't do well up to 4500. Now this Q-jet needed a rebuild bad. I didn't see any aluminum corrosion at all on the base or carb body but it had so much carbon on it. I believe it was a good candidate for a re build though. If you only saw the rest of the motor Loaded with carbon everywhere!!, even on the piston and piston walls below the rings, heads were loaded, inside the block and the mains. Even the valley and the inside webbing was loaded with carbon. I found it had a bent push rod when I took it apart. I remember the junk yard guy telling me it ran great when it came in before they pulled it. Typical Junk Yard guy that you would see in a TV show, commercial or movie, it was comical. He even had cigar snub in his mouth. That I do remember lol. It was only $100 with the ST400 trany so no big deal at the time.
I'm pretty sold on the design aspects of the quadrajet. The fact that GM figured out how to put the same carb body on pretty much any size engine is brilliant to me. The demands of the engine dictate how much the secondaries open and you never have more or less than what you need. They're very tunable, which can be a blessing or a curse. But they can deliver EFI like drivability if tuned correctly.
factory 2 x 4 should be good on a 425 with dist advance more quick coming in. on a tired 401 i could see why not. did the factory even put the 2 x 4 on a 401 ? don't think they did.
No not on the 401 but people were going to the parts department to get them. They most likely were discouraged that their 401 ran no better as like you said the Dual quad Super Wildcat was a package with the recurved distributor and hotter cam. I think just the dual quad was said to be only a 12 hp difference. All the old tests said the best intake was the factory Q-Jet. I have read alot of posts here that they have trouble dialing in the dual quads??
that's not true about the factory Q-Jet intake being better, it was no better than the square bore i have flow numbers from both from Greg Gessler i think i posted some where. it was better only because the Q-Jet was 730 cfm and carter was really only 575 cfm. I know every body say's stock carter was 600 cfm but on research the size of the butterfly makes it 575 cfm
Jim Burek used to mill the stock Nailhead 4 barrel manifold to accept the larger square bore Holley. I always wondered how they performed with or without a 1/2 open spacer. I should have sent him one before the whole Bulldog episode sent him in another direction.
I have to admit i'm just going by a couple articles in the day this being one of them. You have hands on experience and a screamer of a car I couldn't dial in any carb back in the early 80's as they were the wrong ones or in bad shape. The Q-jet was new around 1966 if i'm correct? so it took the testers by surprise i'm guessing. Mentions nor fuel injection or larger carb was better. I'm guessing you have this old magazine.
That seems to be an option now too. I've read that if you pair it up with an AVS2 800 Edelbrock that'll perk it up. Would you have clearance issues with the spacer in lieu of opening up the bores???
is that not just what i said 3 tenths with a bigger carb and air cleaner, am sure they didnt use the stock air cleaner in there run. they said big Q-Jet and not anything about Q-Jet intake. back then there was no 750 edelbrock carbs to use. i don't understand what you are trying to say or where you going with this ? are trying to say only a Q-jet carb could give you 3 tenths ?
Just doing a little chatting and I am admitting that my sole knowledge is by going by old articles in the day when the Q-jet option came to be. Thats why I asked on post #8 if there was a bigger AFB carb than a 625 around 1966. What ever the article means by other bigger carbs I don't know. Your real world testing shows any bigger carb works well or at least the 750 Edelbrock which is a AFB copy? and your 65 puts out some great numbers.
not sure if holley performance carbs were around then but they would not bolt on to a nail head intake. the 750 cfm and open air cleaner i tested were on 401 not on my 65 stroked motor but on one stock and one mild built 401 engines. it helped a lot from 4400 rpms to 5000 rpms. the stock 401 was all done at 4400 rpms making power, but bigger carb and air cleaner raised it to 4800 rpms making power.
