# Opinion on carberater for a 400 motor



## MR70GTO (May 2, 2015)

atriot:WHATS UP GUYS. SO I NEED YOUR HELP I JUST BOUGHT A 70 GTO CONVERTABLE ALL ORIGINAL MATCHING NUMBERS! I JUST HAD A TUNE DONE TO IT AND THE GUY TOLD ME I NEED A NEW CARB AND DONT KNOW WHAT CARB GET  IM NOT MECHANICALLY INCLINED SO IV DONE A LIL REASEARCH AND EDLEBROK AND DEMON ARE THE TWO I HEAR ARE GOODNOT SURE IF I NEED A 600 OR 750?? :banghead::banghead:. I NEED FEEDBACK ON THE TWO AND WHAT YOU THINK IS BEST BANG FOR MY BUCK. AND I DONT KNOW WHAT IT MEANS ELEC OR MANUEL? YOUR HELP IS DEF APPRECIATED

ALSO IT NEEDS A FRONT REBUILD AND IM DEBATING ON WEATHER TO GO STOCK OR UPGRADE A LIL ..HELP ME!!!!! LOL 

THANK YOU 
DANNY:seeya::seeya:


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## chuckha62 (Apr 5, 2010)

First, turn your caps lock off.

Second, Welcome!

Third, use the stock Rochestor Quadrajet! If your mechanic can't rebuild it, find someone who can. It's far better than anything offered aftermarket, in terms of low end torque, economy and performance.

If you ever make it over to Santa Rosa, drop me a line.

Cheers!

Chuck


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## Roger that (Feb 6, 2010)

I assume your numbers matching car has the correct carb. You need to keep that carb if you want to keep that status.


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## MR70GTO (May 2, 2015)

so going after market wont give me better performance and economy?? hopefully i can find someone that can rebuild it..im keeping anything i replace..


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## oldskool (Apr 26, 2015)

*Yes, Keep It !*

I agree with the previous posts. If the carb is indeed the original, numbers matching Q-jet, it is worth a few bucks more than most non-GTO carbs.

But if it is, and you decide to have it rebuilt, make sure you send it to a Q-jet expert, and not some local Chevy mechanic, who prefers a Holley or an Edelbrock, because they can be bought brand new.

If numbers matching is not that important to you, and right now all you want is a good driver, then I'd still buy a Q-jet. Just keep the original in a good safe, dry place. Even if you never use it, your car will be worth more, if you decide to sell, with as many original parts included as possible.

Cliffs High Performance Quadrajets :: Quadrajet Part Numbers - Carburetor Numbers - Carb Rebuilding, Quadrajet Rebuild Kits, Bushing Kits - Parts

Cliff Ruggles is considered one of the best Q-jet guys around. He wrote a very good Q-jet book. He is usually backed up for months, on Q-jet builds. But his rebuild kits are considered the best, by many. Several good Q-jet guys buy all their kits from Cliff.

Cliffs High Performance Quadrajets :: Quadrajet Rebuild Kits, Qjet Carburetor Rebuilding, Carb Tuning, Bushing Kits and Parts

There are a lot of good Q-jet guys around, who don't advertise. There are probably some that post on this forum--don't know. Here are a couple of places I've heard good things about. 

Everyday Performance Rebuilt Quadrajet Carburetor Store ~ Quadrajet Carburetors for Sale

SMI Carburetor Street Performance Rochester Quadrajet 800CFM Buick, Oldsmobile and Pontiac Quadrajet 4BBL Rochester 4BBL Quadrajet 800CFM for Pontiac SMI- Sean Murphy Induction

I've read both good and bad reviews of the Jet brand Q-jets.

Performance Carburetors - JET Performance Products, Import & Domestic Performance, Performance Kits, Fuel Systems, Transmissions

Here's some more I've run across. Haven't heard anything good or bad, about 'em. I have heard that the worst place to buy a Q-jet is from one of the really big carb rebuilders or a parts store. They have a rep of poor quality builds, with mismatched parts. 

Sparky's Carburetor Service

Carb Junky's Professional Carburetor Rebuilds & Restorations

items in store on eBay!

MIKESCARBSHOP.COM

Another Q-jet guy with a good rep, posts as Maryland Bandit, on the transamcountry.com forum. Don't have a link to his business.

Login


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## MR70GTO (May 2, 2015)

Really appreciate the good info guys. I spoke to a couple buddies who have had qjet in there gto and they swear against it???? There telling me there junk and not to rebuild it and that I'm waiting my money if I do. How much does a rebuild normally cost?


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## oldskool (Apr 26, 2015)

*Cost*



MR70GTO said:


> Really appreciate the good info guys. I spoke to a couple buddies who have had qjet in there gto and they swear against it???? There telling me there junk and not to rebuild it and that I'm waiting my money if I do. How much does a rebuild normally cost?



Hey, most of the guys use to tell me to race a Chevy. Thank God I didn't listen !

And to all the guys who say the Q-jets are junk, I'll just be REAL nice, and say that they don't know what the heck they are talking about ! It's too late to tell me they don't work. We've won far too many races, with nothing but Q-jets.

And every street Pontiac we had also ran a Q-jet. And there are LOTS of 9, 10, and 11 sec drag cars running, and winning with Q-jets. There is just far too much evidence in favor of the Q-jet, to be swayed by those Holley lovin Q-jet haters ! IMO


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## MR70GTO (May 2, 2015)

Lol I think I'll try to rebuild it and see from there.. Hopefully I can find someone I'm Sacramento that can do it..


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## chuckha62 (Apr 5, 2010)

That's a typical response by guys who just don't know what they're talking about. The Quadrajet is much maligned because it is misunderstood. It is a complicated carburetor compared to a Holley or a Carter (Edelbog). The problem with the Quadrajet is almost always due to the last guy who worked on it. Once it is properly rebuilt and tuned to your application, it will give many years of trouble free service.

Due to the vacuum opened secondary air dump (which also pulls the secondary metering rods), the Quadrajet flows 750 (or more) cfm without overcarbureting at part throttle or during transition to full throttle. It can be tuned to work VERY well throughout the range. 

The important thing with respect to low-end performance is intake velocity and the small primaries on the Rochestor spreadbore get velocity up much quicker than a similar CFM Holley. 

As for good rebuilders, Cliff Ruggles is/was backed up at least a year the last time I spoke with him and while he is the best, there are other good builders out there. Ask around and you'll find one. In Norcal, I know there is a guy in either Morgan Hill or Gilroy (or that vicinity) who is supposed to be very good.

Good luck and don't give up on the Rochestor. You'll piss off your buddies when you stomp them on the strip and get better mileage getting too and from to boot.

Chuck


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## tguggino (Aug 31, 2013)

Great info on carbs. Hijacking the conversation, Can a Qjet be made to work with a stock 64 GTO manifold? 


Sent from AutoGuide.com Free App


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## PontiacJim (Dec 29, 2012)

tguggino said:


> Great info on carbs. Hijacking the conversation, Can a Qjet be made to work with a stock 64 GTO manifold?
> 
> 
> Sent from AutoGuide.com Free App


It may be possible with a carb adapter. Here is one that may work. Look at the manifold bolt pattern specs and see if your '64 manifold has the same spacing. http://www.summitracing.com/parts/edl-2692/applications


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## tguggino (Aug 31, 2013)

Thanks. I see re-manufactured QJets on Summit for $330. Chevy. I assume these are not the recommended units you all are talking about.


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## oldskool (Apr 26, 2015)

tguggino said:


> Thanks. I see re-manufactured QJets on Summit for $330. Chevy. I assume these are not the recommended units you all are talking about.


You are correct. These are NOT the carbs we recommended. There is no telling who rebuilt them or what the quality is. 

But, you may be able to buy a good quality one for near the same price. I'd check with Everyday and see if they have a lower priced one with a straight inlet. If you buy a '71-'79 Pontiac model, it will have the big "smokestack" vent, which requires a hole for it in the air cleaner base.

So, for this reason, I'd prefer a Buick or Olds model(may require linkage mods), or even better a '68-'70 Pontiac model. However, these older carbs are now harder to find, and too high if they came off a 400 Firebird or GTO. Most of the Musclecar Q-jets are in demand for high dollar numbers matching restos. 

http://www.everyday-performance.com/quadrajet_carburetors.htm

There's nothing wrong with a side inlet Q-jet. You just have to do a little extra plumbing with the inlet hose. If you don't mind using a side inlet model, the best buy listed on the Everyday site today, may be the '73 454 Chevy carb, for $250. May also be easier to sell, since most of the cars in the world seem to be Chevy.

http://www.everyday-performance.com...adrajet-7043200-SS/p/18005702/category=578011

There are usually several rebuilt Q-jets on Ebay. I'd say the quality will vary greatly.

http://www.ebay.com/sch/i.html?_odk...t+rochester+quadrajet+carburetor&_sacat=33550

Of these on Ebay, these 2 look promising, for a Pontiac. Again, I have know idea of the quality of the builds.

http://www.ebay.com/itm/ROCHESTER-Q...ILT-/121515173239?hash=item1c4ade6577&vxp=mtr

This '77 Buick model should be an 800cfm, has more adjustment than the '74 and earlier models, and can be easily fitted with an electric choke if desired.

http://www.ebay.com/itm/Rebuilt-Roc...tor-/251695682786?hash=item3a9a3b54e2&vxp=mtr

This earlier Buick model may be a good rebuildable core--who knows ? It has the slashed vent and supposedly came off a 455, so it should be an 800cfm. Cliff says this is one of the best of the early carbs.

http://www.ebay.com/itm/Big-Block-G...evy-/161691658340?hash=item25a592e864&vxp=mtr

And here's a pic of one of the Pontiac "smokestack" models. Don't say if they actually have any of these for sale.

http://www.ebay.com/itm/ROCHESTER-Q...ILT-/111522924826?hash=item19f748c91a&vxp=mtr

http://stores.ebay.com/SOUTHERN-CARBS-AND-RC-HOBBY


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## chuckha62 (Apr 5, 2010)

You'd be better off finding good, complete, original cores. Buy Cliff's book and go through it yourself. 

You MIGHT get a good unit from one of those Ebay retailers, but it's a crap shoot.


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## Pinion head (Jan 3, 2015)

tguggino said:


> Great info on carbs. Hijacking the conversation, Can a Qjet be made to work with a stock 64 GTO manifold?
> 
> 
> Sent from AutoGuide.com Free App


4 bbl adapters (squarebore to spreadbore & vice versa) are more of a patch job, & decrease efficiency of the engine as an air (and atomized fuel) pump. Have never ran across a Qjet adapted performance built Chebby or Pontiac engine that didnt perform better with the correct matching intake.Realize that's a problem if trying to run a properly built Qjet on a '61-64 Pontiac AFB intake. Dead set on running a Qjet on the '64 heads, I'd go down the route many others have and extend the intake mounting flanges of a later style intake. been done with '66 tripower intakes, both original, and with the alum repro's, could be done with a '67 and later Qjet intake.

On commercially avail Qjet rebuilds, I'd avoid them like the plague. Have no use for generic metered Qjets. Have also ran across too many times staked in seats, and nasty Tomco fitting in the fuel inlet. it's better to start out with a quality core. as far as Qjets go, Cliff's Qjet book is the best money I've spent in the last 20 years. Have been personally rebuilding Qjets since 1980 and Doug Roes Quadrajet book, HO Racing tech sheets, and disassembly and rebuild of multiple dozens of factory performance and RA Q jets only took me so far. Reading Cliffs book and being able to understand specific mods, APT circuitry, etc, can only be compared to going to grad school.


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## 67Twistytee (Feb 24, 2014)

I used Doug Roe's book and Cliffs book to rebuild my back-up Qjet. Got the kit from Cliff and took my time. Came out great and felt the photos/techniques in the books took a lot of mystery out of the process. Someone previously had worked on my original '67 Qjet and flared the fuel inlet. I sent this one into Cliff for some machine work to fix the leaking inlet. I also had him re-color the carb. Came out great. His shop seems to be getting caught up on the back-log as the wait time was about 6 months.


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## BearGFR (Aug 25, 2008)

+1 on the QJet. I run one on my 69, and it runs 11's at the track  The only people who don't like them are the people who are too dumb to understand them, to be blunt about it. Also, most of the problems with them are a result of 'the last guy who worked on it'. There's a lot of folklore and "trick of the month club" information out there about these carbs, most of it just plain b.s. If you can afford the very lengthy wait (and I mean potentially a year or more) then Cliff is the best. If you're mechanically inclined yourself and are willing to take your time and be careful, you can do it yourself using his book as a guide.

Bear


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## MR70GTO (May 2, 2015)

I think I'm going to go with my Qjet I found a guy that really knows pontiffs and says that I really don't need a rebuild and that mine works fine so I think next is head and headers which I'm leaning towards the ram air vs hookers headers what do guys think?


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## chuckha62 (Apr 5, 2010)

MR70GTO said:


> I think I'm going to go with my Qjet I found a guy that really knows pontiffs and says that I really don't need a rebuild and that mine works fine so I think next is head and headers which I'm leaning towards the ram air vs hookers headers what do guys think?


100% agree on the ram air manifolds. Headers on these cars are a pain in the ass and offer a negligible performance benefit (if at all) over the ram air manifolds. Bottom line is that the ram airs fit and headers never seem to. Additionally, if you're going to run your car at lower than stock height, headers will bottom out on speed bumps, driveway transitions and other minor obstacles.


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## Docjim (May 8, 2015)

Hi Mr70GTO

I do have an opinion on this subject. I have a 67 with a stock 400 and tried about every carb you could on it. I have access to a dyno so we also were able to document results. As others said, hard to beat the old Quadrajet for all around driveability. Here is my assessment from the results we did.

Holley: Pretty much old school. They run good but need some tuning and still have the proverbial stall in the midrange

Edelbrock: Good driver carb. Starts and runs great. Driveability very good. The drawback is they did not dyno the HP as good as some of the others in the same CRM rating

Demon: Good horsepower but one of the hardest to get tuned correctly. Not as good as an everyday driver carb.

Quadrajet: Starts and runs great. Good horsepower and probably best fuel mileage. It also has the orginal factor


Best carb tested was a Quick fuel 680









The best we tested was the SS-680-VS with electronic choke. Bolted it on and the only tuning we had to do was idle screws and choke idle adustment. Pretty much bolt on and go. Great starting, great driveability and best HP tested. I still have it on the car and wouldnt change it for any of the others.

Its hard to get good opinions on this subject on the internet because you dont know who is responding. Could be someone working for the carb company trying to sell you a carb. I am just an old GTO guy with access to the dyno and some guys that know how to tune. This is just my opinion. Good luck with your car. I hope I helped out a bit. Docjim


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## MR70GTO (May 2, 2015)

Thanks doc it did!!


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## MR70GTO (May 2, 2015)

chuckha62 said:


> 100% agree on the ram air manifolds. Headers on these cars are a pain in the ass and offer a negligible performance benefit (if at all) over the ram air manifolds. Bottom line is that the ram airs fit and headers never seem to. Additionally, if you're going to run your car at lower than stock height, headers will bottom out on speed bumps, driveway transitions and other minor obstacles.


Ya chuck that's what I hear from lots of gto guys. And plus i think it will hold its value better.. Any good sites to order the kits and manifold besides eBay ,OPGI,and ram air reproduction..best deal???:biggrin2:


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## oldskool (Apr 26, 2015)

*Ss-680-vs*

I checked out that QF carb. It's $527 at Summit. But if you got the $$ and want a square bore Holley type carb, they got 'em for sale.

http://www.summitracing.com/parts/qft-ss-680-vs

I'd prefer an 800cfm SMI Q-jet for $399, if I had that much $ to throw around. 

http://www.smicarburetor.com/products/sfID1/28/sfID2/9/sfID3/100/productID/838


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## Docjim (May 8, 2015)

oldskool said:


> I checked out that QF carb. It's $527 at Summit. But if you got the $$ and want a square bore Holley type carb, they got 'em for sale.
> 
> http://www.summitracing.com/parts/qft-ss-680-vs
> 
> ...




A couple of notes from the dyno tests. No matter what the CFM was some out performed others. The Quick fuel was a 680 CFM and the Quadrajet was an 800. The quick fuel put out 15 more horse than the Qjet and thats a ton for just a carb swap. We tried 750's on the stock 400 and in every case they were too much. The lesser CFM carbs were much easier to tune, better driveability and starting and were within a couple horse of the big CFM carbs. Big CFM is not the best way to go in all cases. Any square bore performed better at 700 CFM or less. Again the Qjet is the best for originality and they do perform well all around. My car just really like the 680 Quick fuel.

Some assets of the quick fuel are four corner idle. They keep fuel flowing at idle so when it comes time to kick it down, the fuel is there and that carb hesitation is gone. QF also redesigned the venturies for more efficient flow at closed throttle positions. Carbs work great at wide open and are as good as fuel injection at wide open. Were carbs falter is in the low and mid open positions and thats were we do most of our driving. Its also why fuel injection is more efficient and better mileage. They control lower speeds better. These modifications make an old design way more efficient. Thats why these are more money. Billit metering plates and such at to the cost also. There are cheaper. But our tests showed this one to be the best on a stock Poniac 400. Again I hope that helps. Please also understand this was our tests and my opinion. I just heard so many comments about carbs throughout the years I had to test them and see what works for my own knowledge. Doc


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## oldskool (Apr 26, 2015)

Hey Doc, maybe you oughta send this info to QF. They could probably use it for advertising, to help sell some of their $500 carbs. Hey, it's worth a shot. Who knows, it might make you famous.

But hey, I don't know you, so you may already be famous, for all I know.


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## Docjim (May 8, 2015)

oldskool said:


> Hey Doc, maybe you oughta send this info to QF. They could probably use it for advertising, to help sell some of their $500 carbs. Hey, it's worth a shot. Who knows, it might make you famous.
> 
> But hey, I don't know you, so you may already be famous, for all I know.


LMAO! Im nobody like I said just a guy with a GTO that wanted a good working carb. No advertisement just my experience. I bought two on Amazon for $450. One for my 400 and one for a 383 Chevy for a friend of mine. I didnt think the $450 was really out of line. We did try the HR QF on it also but it ran much like some of the others we tested. The SS was the carb to get. Ya I get pretty stubborn when I find something that works. For instance, back in the day, I found the stock Ram air III exhaust manifolds worked better than headers. Maybe it was the headers back then but I felt better torque with the stock manifolds. Ran them on all the GTO's I had even when I was heavily pressured to get headers.


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## oldskool (Apr 26, 2015)

*RA3 Manifolds*

Yeah, my original RA3 Goat won lots of races with those manifolds on the original RA3 engine. It had over 60,000 street miles, but still ran good enuff to win at our local track. 

I had a muff shop make me some header pipes, stepping up from the 2 1/4" connection to 3" collectors. Some would look under it and think I had headers. But I'd raise the hood and prove 'em wrong.


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## Jared (Apr 19, 2013)

I have a 600CFM Edlebrock on mine. It was on the car when I bought it. Since I don't race, this carb has been fine. The only issue I have encountered is it seems to run out of gas if you hold it at full throttle for too long. Say a real good pull on a highway on ramp. Almost feels like the fuel bowls are empty. Other than that, no issues. I was tempted to change it but it runs too good to mess around with and I rarely run it very hard anyway. Not sure what mileage others get, but I see low to mid teens on the highway.


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## SpeedSLC (May 24, 2015)

Hi Ihave been searching to make sure mut gt is #s matching. I knoiw the clock is but U don't know where to find the identifiers for carb, transmission and whatever elsse there may be


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## Pinion head (Jan 3, 2015)

Matt, the original Q-jet for a '71 400 stick A or F-body is a 7041263. Originals were only made by Rochestor Products, there is service replacement "1263" Qjet made by Carter, but it is nowhere near as desirable. The roll stamped part number, date code, and two letter pick code are stamped on upright flat area of the the fuel bowl several inches behind the throttle shaft. 

On the transmissions, if yours is a Muncie 4spd, it should be a "661" case M20. Will post more info...


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## Irishmic (Sep 24, 2013)

Nice thread !!


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## dan woodland (Jul 24, 2013)

Good information here... 

FYI: I just rebuilt a Quadrajet (68 Firebird 400 Auto) for $18 with a new float!! 

I've never rebuilt one, before last month, but with all the on-line videos it's pretty easy to learn without even touching one!!

A few pics to give you and idea... didn't even use the instructions, took it apart, made note of the pieces parts and did the reverse to put it back together.



The cause of my need for a rebuild...


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## oldskool (Apr 26, 2015)

Looks like a black worm crawlin outa that primary jet. Is that an early Halloween pic ?


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## dan woodland (Jul 24, 2013)

Ha, no it was a piece of fabric!! There was another in the other jet!!!



oldskool said:


> Looks like a black worm crawlin outa that primary jet. Is that an early Halloween pic ?


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