OK, a week or so ago I started a thread about why people liked or disliked Holley or Edelbrock carbs. A few people mentioned Quadrajets, and I kind of liked the idea of saving some cash by getting and old Quadrajet, rebuilding it, and tuning it, but I thought I might get some feedback on what HAMBers thought of Quadrajets compared to Holleys and Edelbrocks.
Why not just get a used Holley and rebuild it. Better yet, get a used Holley and try it out, maybe it doesn't need rubuilding. Later Josh.
Search quadrajet and Q-jet. There is a new book out that is supposed to be even better than the Doug Roe book that I recommend. I'll put it in perspective, two carters (What Edelbrock copied) look cool on a Nailhead, but the single Q-jet makes more power. They also work well enough for ford to use them on the Super Cobra Jet motors. There was even a modification developed on the ford project that makes them work better. My two cents.
I guess it is your time and money. I hate saying it because I dont like it being said to me but there was Thread I put here about 1 year ago asking for stuff on Quadrajets and i recall a link that was great. I am not at home right now so i can not retreive it from my documents to post. But search around a little and see if some of that stuff helps as well as any new posts that you may get here. For me quads are great for making horse power but they seem to drink fuel and are quite noisy i thought whereas holleys are just so simple and they are great when running right and easy to fix when they are not.
The only problem I've found with getting an old Qjet and rebuilding it and running it is that you usually need to get about 4 or 5 before you find a good one. But it's been worth it for me...I've been running them for years on mild street engines.
i can tell you the secret trick on the super cobra q-jets if you want seriously though, i LOVE quadrajets and would pick them over ANY other 4bbl on anything but a strip only engine. i rebuild carburetors as a side business and specialize in them. i got 14mpg around town out of a 450hp big block olds in a 4000lb car with one. this was a low 12 sec car btw. plan on running two of them on that engine with a new cam. i'll set them up like the quadrajets used on the poncho 230 OHC. i also have a parts supplier that i use that sleeves the throttle shafts with bronze for around $60 so you don't have to worry about it ever again. if you get one get a 4MV version built before 1975 rather than the later 4MC. they have much more options for performance parts and only the 71-75 ones were emissions carbs of the 4MV.
A great carb when it's setup and rebuilt properly. I've been doing them for a few years now. They can make just as much power as a Holley and be easier on fuel also. The book I believe Stevie G is referring to is How to Rebuild and Modify Rochester Quadrajet Carburetors by Cliff Ruggels. I have it and it is an EXCELLENT book on Quadrajets.
The drilled emulsion tubes really woke up the engine I was building. Has anyone tried drilling the metering ckts? I've heard good reports and bad; just wondering how tricky it is. It's the one mod I haven't tried yet.
You might be surprised to learn that a properly calibrated Q-jet can run right with any Holley on hot street engines and in moderate race applications. On the street the Q-jet will also get better fuel mileage, and still give up nothing to the Holley. It seems most folks won't give the Q-jet a try because it doesn't look 'racy' enough or because they think it's too complicated. THE book on Q-jets, by Cliff Ruggles, with all due respect to Doug Roe this new Q-jet book is light-years ahead of the old stand-by: http://www.amazon.com/Rebuild-Modif...bs_sr_1?ie=UTF8&s=books&qid=1219981161&sr=8-1 Check out the posts by Cliff in this thread, he helps out people all the time on the PY forums and he doesn't bullshit:http://forums.performanceyears.com/forums/showthread.php?t=461361 I run one of his 800 Q-jets on my GTO and it runs perfect, if I had the time I would have used his book to build and calibrate my own.
I've always been a fan. Typically I hear negatives. Glad I'm not alone. They are dirt cheap at the bone yard too.
Don't rule out those little economizer carbs Holley made to fit the Qjet manifold. They don't look like a holley and they are real efficient. I love them, but the kits are really expensive for rebuilds and hard to find. At only 450 cfm they are small, but work well even on mild big blocks. Holley had to quit making them as the BIG THREE and Oil companies didn't like the idea of better fuel economy on muscle cars and hot rods. At least thats the rumor...
I put an economiser on my ex wife 327 68 Camaro years ago. It was so slow she wanted it gone NOW. A pos!
fine then, i won't tell you! lol it's not too tricky on the circuit drilling, but not a bad idea to practice on some junkers first.
Q-jets are great carbs IF they are built and set right. It is an art, though. They always got a lot of bad press when guys who didn't know how were setting them up. Hence, the moniker, Quadra-puke. Have someone who knows what they are doing re-build it, and I think you'll be happy w/it.......
Best all around carb in my opinion. When set up correctly they not only perform well but hold their tune forever.
yep. i have them on my 455s. work great. but you do have to know how to set them up or you will get the "quadra-bog" i have an edelbrock on one of my 401s and had a demon on a 500hp 455 and they all work great. it is just a matter of tuning. i'll second the fuel thing. it is great to be able to putt around on a q-jet and then lay into it opening the grapefruit size secondaries sucking in mail boxes and small children! if you want to go real odd ball get a rochester 3 barrel
Greatest vacuum secondary carburetor out there, if you can just keep the fuel wells sealed. Have personally had porosity/leakdown issues even after epoxying the wells. Dunno what happened, in the last 10 years haven't been able to get one to seal for shit. Maybe fuel additives changed, maybe the alloy is aging poorly, maybe I've just had bad luck. Gave up and tried an expensive SMI Q jet. It started leaking in 6 months too
Base(?) "429 Cobrajets" had the Rochester Quadrajet carburetor...the "SUPER Cobrajets" had a Holley carb. The Quadrajet was bigger than anything Ford had available flow wise so they needed it as a street carb to feed those huge 2.25 Intake valves. It even had a tag with a Motorcraft part number! The Holley carb was the latest thing on the strip so that went on the Super Cobras as it was a bit easier to tune at the track. 429 Cobrajets are a wild engine!!! Just wish Ford had kept going on performance development...but sadly the insurance crackdown, pollution fiasco and gas crunches saw that would never happen. Regardless...The "CHEVY" Quad was used by Ford on its most advanced and powerful street engines of the day...because nothing else could give as much performance with as few warrantee issues as a big Quad. Says a lot... I plan to run one myself!
Kinda of wondering why you said you have to get 4 or 5 to find a good one. I have dug old carbs of various types out of the junkyard and rebuilt them with out any problems. Is there something I should particularly look out for with the Q-Jets?
They're getting old....lots of them have been abused by having the bolt tightened too much, warping the body and air horn, or having been thru the "factory" rebuild process, etc. If you can find a nice unmolested Qjet first try then you should be fine.
I'm cornering the market on the kits right now, I'm going to use Fat Hacks idea of using them on a 283 and an Offy low rise 2x4, all 8 barrels the same size.
So!!!! It's your fault I can't get any kits..... That's ok, I have a few already and I have even more carbs... Good to see someone else likes those little controlled leakers too..
On the upside, I can still buy complete used late '60s/early '70s Q-jets at swap meets for $5.00. At that price, you can afford to stock several.
a buddy of mine has a couple 5 gallon barrels full of em, unmolested and all needing rebuilt probably. Why?? We don't need no stinking Q- jets. Not that they are a bad carb "when they work" but never saw the advantage to rebuilding them
right on with "Cliff Ruggles" I have spoke with him on the phone about a few hick-ups. he is good with q-jets...he mentioned something about, he can have them idle a pro-stock engine before, & that definitely got my attention.
Look for one off a boat tail Riv - that's an 850CFM unit legend has it, and I think the highest CFM Q-Jet ever made. ~Jason
i got a couple, one has been kitted a couple of times i wouldnt part with it , it came off a old 402 chevy from the factory maybe 325 hp? runs great on mild 350s . now useing it on my stock 307 olds with 50 hp shot of no2. the plugs look perfect ,just adj. the sec. air doors a little.
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