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1967 Q-jet Carb Question


60s GM Fan
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Can someone tell me what 4GC I should have on my 1967 Wildcat?  I have someone trying to fix the one thats currently on my car and according to him someone Frankensteined the hell out of it and its not running as good as it should.  If he can't fix it then I'd like to find a properly rebuilt one for my car.

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Far as I know that engine should have either Rochester QuadraJet or Carter AFB carburetion. 4GC last used in 1965 to my best knowledge.

 

With the carb off the engine, are all four holes in the intake the same size, or are the rear holes (secondary side) noticeably larger? Same size=4GC or AFB, larger=QJet.

 

Or is it possible you meant 2GC, which is 2-barrel Rochester carb used on into the 1970s? Though a Wildcat 430 should be 4-barrel.

 

www.sparkyscarbs.com

 

Greg Kalkhoff has an excellent reputation in Oldsworld and can properly service and restore almost any non-electronic GM carb.

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As we used to say, beer can sized secondary holes on a Quadrajet!

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3 hours ago, 60s Buick Fan said:

It was missing a seal or two originally and the metering rods weren't there either.  Its a mess according to him.

😳

 

A QJet with no metering rods/power piston is not meant for a street driven engine. There are a VERY few factory high-performance applications that do not use them. Before trashing this carb, get the ID numbers off it and let us know if it's side inlet or front inlet. You may have a desirable carb on your hands.

 

Then again you may have a cobbled-up mess created by someone who read a QuadraJet book and thought "I can do that!"

 

I'll be completely honest. I'm leery of most commercially rebuilt jobber carbs. Some have the right stuff inside but a lot have whatever was in the rebuilder's parts pile. 

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6 hours ago, 60s Buick Fan said:

He's had it apart 5 times and he still feels its not running 100%

Maybe twice in an extreme situation. What does this "feels" mean?

Even if the carb has been screwed up a handful of parts from a core or an Ebay sales should get it back into operation.

 

As described it sounds like someone was trying to use it as a secondary for a 2X4 setup. I know a couple of locals who might do that but they don't live right in the village.

 

The proper approach is to take the car to a mechanic and say "Car don't run right. Fix it."

 

 

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So it turns out the carb is actually a 1971 Chevy carb for a manual car.  He's got it running great on the primaries but he said the secondaries just drown the car out.  I'm going to just have him button it up as is now and look for the right carb.

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3 hours ago, 60s Buick Fan said:

So it turns out the carb is actually a 1971 Chevy carb for a manual car.  He's got it running great on the primaries but he said the secondaries just drown the car out.  I'm going to just have him button it up as is now and look for the right carb.

 

Good choice!

 

Lots of folks think they can make any Q-Jet work on any application because they are virtually all the same size (750, 800, and a VERY few 850's)

 

I can count the number of folks that I personally know that can do this on the thumbs of my left hand (and it isn't me!).

 

One of the worse messes I ever got into was a GTO carb that just wouldn't idle, even after a pretty sharp local rebuilt it. He brought it to me (he's still a good friend, even after bringing me this pile of *&^%$). I took it apart, and at first blush it looked great. Then starting checking air bleeds, restrictors, etc. and found some previous owner had obviously wanted to run this thing on a Chevrolet, and had installed Chevrolet idle air bleeds. So the carb had TWO sets of idle air bleeds, both the Pontiac and the added Chevrolet ones (Chevy and Pontiac used air bleeds in a different area of the carb). Would you believe it was VERY lean? Fabricated some threaded plugs and installed in the aftermarket Chevy air bleeds with red loctite, and it ran great. How many enthusiasts that have rebuilt a few carbs are going to look for, or recognize this bit of chicanery?

 

Not a hard and fast rule, but a good rule of thumb when it comes to carb calibrations, is there is Chevrolet, and there is everyone else! Trying to migrate a Chevy carb to anything else, or a carb from anything else to a Chevy requires WORK!

 

In the FWIW category, the 1967 Q-Jets still had a couple of design problems. They CAN be overcome, if one knows what one is doing, but Rochester released service replacement Q-Jets for the 1967 Buick, and they require less mods, and are far more reliable. NOT GRINDING MY OWN AX, I DON'T HAVE ANY, DON'T ASK! Just providing info. Unless the car is numbers matching, I would suggest checking some of the Buick folks for the SR carbs.

 

As Glenn mentioned, there are a VERY FEW Q-Jets that did not have primary rods, piston and spring; but you have a better chance of winning an argument with the IRS than finding one! I think in the last 50 years, I have owned two, and they are long gone.

 

Jon.

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For a normal OEM-spec QJet, if it bogs down on the secondaries, it means the secondaries are openning too far too quick, from my experiences.  Best to fine a QJ that has not been molested!

 

The QJ is a pretty neat-designed carb, from what I can tell.  LOTS of flexibility, which is good.  BUT I concur that they are not nearly as universal as some might believe.  When I got the S-A Designs book on Rochester carbs, I was amazed at the humongoug number of primary metering rods, power piston spriings, and secondary rods for the QJ.  It was good that the specs AND GM part numbers for each one of those was listed in the book! 

 

NTX5467

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I am being told that I need a 7027240 or a 7027244 w/o A.I.R. for my car (non-CA emissions).  EmTee gave me a link for what looks like a very nice rebuildable core plus other shops that have rebuilt cores for sale.  I'm not too keen on Carb Center as they sent me a 1958 Chevrolet Impala carb for my 1955 Cadillac Coupe Deville.  While it works to get the car running/driving its not the correct application and even with that carb I've noticed some performance related issues.  What's everyone's opinion on Quadrajet Power?  If they don't have what I need then I'd like to use either Sparky's or someone else to rebuild a correct core.

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22 hours ago, carbking said:

there are a VERY FEW Q-Jets that did not have primary rods, piston and spring; but you have a better chance of winning an argument with the IRS than finding one! I think in the last 50 years, I have owned two, and they are long gone.

 

Jon.

The last 1970 Olds W31 (one of the engines that didn't use metering rods) QuadraJet core I even heard of sold for over $1000.00 and needed a complete rebuild including throttle shaft bushings.

 

OP, I have no personal experience with QuadraJet Power. Suggest digging around on classicoldsmobile.com or v8buick.com to see what people there say. 

 

I can vouch for Sparky's and,  for 4GC, Don Monroe in Washington state. 

 

Jon can elaborate on this, but whoever you choose to do your carb, look into rejetting it for this crap ethanol fuel unless you have a reliable source of 93 octane non-ethanol gasoline. Going one size larger on both primary and secondary jets (not metering rods) will help.

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But, what is your altitude? Not sea level, right?🤔

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91 "Pump octane" is pretty close to the old "95 Research Octane" level (normal Regiular fuel from when the car was built).  That elevation is the reason the only Super Unleaded is "91 Pump Octane", I suspect.  The "100 Octane" is Research Octane, for refeference.  "100 Research Octane" = 95 "Pump Octane", from what I remember seeing in 1974, as the old Phillips 66 FliteFuel had a posted Pump Octane of 95.5 in 1974, in Lubbock, TX.  Which makes "93 Pump Octane" = "97 Research Octane" ("Premium" gas in 1957).

 

The "thinner" atmosphere, at even 1600ft elevation, decreases the octane requirements of the fuel, UNLESS you add in a few more degrees of initial spark advance to make up for the thinner air, by observation.

 

Enjoy!

NTX5467 

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27 minutes ago, 60s Buick Fan said:

EmTee to the rescue!  I've sent a PM to the guy.  Hopefully this works because trying to find this carb has been hell...

Which is probably why the Chevrolet lump was on there in first place.

 

Buick, Olds and Pontiac used the side fuel inlet QJet only in 1966 and 1967, switching to front inlet for 1968-later. Chevrolet OTOH stuck with the side inlet forever.

 

Even though having a correct carb is the best and preferred way to go, you might be able to substitute a 68-later Buick application carburetor if you can find one with the correct divorced choke mechanism. You would have to use a later front inlet steel fuel line which I would think is available reproduction, since Olds and Pontiac applications are.

 

Good luck. Hopefully your swoopy Burick will soon be rid of its POS (Previous Owner's   Stamp).

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4 hours ago, rocketraider said:

Hopefully your swoopy Burick will soon be rid of its POS

There are some companies quite proud of their ability. Maybe the helpdesk would respond.

GasPos

 

The little village diner I stop at a couple times a week gets visited by a service truck boldly lettered "We service POS equipment". it's actually the point of service cash register. But the mechanic was taking a break one day so I walked over a told him I had worked on a lot of that equipment myself. Seems to come from the low bidders in my work.

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Based on what this well-known and highly regarded QJet builder and tuner had to do to this new repop carb to get it anywhere near functional, I would stay far away from these. There's a rebuildable correct number ORIGINAL ROCHESTER core out there somewhere. 

 

https://www.corvetteforum.com/forums/c3-tech-performance/4523417-new-chinese-q-jet-inspected-evaluated-and-tested-the-complete-results.html

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WOW!

 

But look at it this way: if you have several thousand dollars worth of test equipment, several thousand more dollars worth of spare parts, a lifetime of experience working on carburetors, AND your time is worth nothing, then its cheap! ;)

 

Glenn - thanks for posting this link!

 

Jon.

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These carbs, like Holleys and E-brock AFB/AVS, are aimed at the guy who wants a bolt-on (😄😆🤣) new fuel delivery system. Supposedly already set close to a moderate Chevy 350's needs.

 

We all know close usually doesn't win the cheap cigar and all carbs need tweaking for best results on a specific engine. 

 

Lars had to basically remanufacture this thing. IDK what these "new" QuadraJets sell for, but doesn't look like a good return on money spent to me. Not when there are good cores and highly competent carb guys around.

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All the more reason expensive and hard to find original carburetors are cheap at almost any price. Sadly, 95 percent of the driving public have no idea if their pre 1975 car is actually running correctly. The further back you go, the less clue they have.

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14 hours ago, rocketraider said:

These carbs, like Holleys and E-brock AFB/AVS, are aimed at the guy who wants a bolt-on (😄😆🤣) new fuel delivery system. Supposedly already set close to a moderate Chevy 350's needs.

 

We all know close usually doesn't win the cheap cigar and all carbs need tweaking for best results on a specific engine. 

 

Lars had to basically remanufacture this thing. IDK what these "new" QuadraJets sell for, but doesn't look like a good return on money spent to me. Not when there are good cores and highly competent carb guys around.

 

Lars didn't remanufacture this thing, he re-engineered it, then remanufactured it.

 

The internet has spawned some interesting habits among its readers: (1) and this is not new......initial cheap price, regardless of the final price, and (2) instant gratification.

 

Sometimes something is scarce enough that no one has scanned it and put it on the 'net so it can be accessed for free, and somewhat difficult to find. And when one actually finds it for sale, the price may be more than ones expectation.

 

Lars did mention a $250. initial price.

 

Jon.

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