unjunking the quadrajunk

[HotRodPC]

Former owner put an Edelbrock on my truck and it is fine and I'll keep it, but I wouldn't personally choose to do that. I've also got a 1977 Cadillac hearse, 425. Gets used mostly in October, often sits for more than 6 months at a time without being even started. It left the funeral home in the late 90's and since then has never has a rebuild on the Q-jet, don't know about before then though, but it still operates just fine.

I'd imagine it's low mileage being a hearse??? Throttle shafts may not have worn the base plate to badly yet. Probably rarely moved the secondary throttle shaft at all.

 

[SirRobyn0]

I haven't seen him in a minute, and don't recall his name but we have a resident Qjet builder here that does them right with the proper mods and fixes. Not sure if he's cheaper than national and not sure if national requires a core. Our guy here, you ship him yours and he ships it back.

I don't use national often as we do most rebuilds in house, but I believe I paid $239 from them last time, frankly I'd rather use a small business or guy that is good at it vs a big corp. That's just me.

 

[SirRobyn0]

I'd imagine it's low mileage being a hearse??? Throttle shafts may not have worn the base plate to badly yet. Probably rarely moved the secondary throttle shaft at all.

116,000 miles, but who knows how many hours of idling, it came from Houston, so I bet it idled a lot to keep the A/C running.

 

[HotRodPC]

I don't use national often as we do most rebuilds in house, but I believe I paid $239 from them last time, frankly I'd rather use a small business or guy that is good at it vs a big corp. That's just me.

Totally agree. Being that carbs aren't near as popular today, carb shops have all closed up. Mail order is about the only way to get one. Perfect biz for an old retired mechanic to do out of his own garage for supplemental income. Provided he's set up right all the proper cleaning equipment, that's who I'd use. I've really considered it myself since they're alot lighter than transmissions.

 

[Octane]

I have a 40+ year old quadjet and only thing its ever had was a accel. pump done one time.It has only recently started with the sticking float.I've used stabil in it for the last 18 years or snly Holley I ever bought was an Economaster brabd new, it sucked more gas than the quadjet and I took it off and never knew what became of the pos.Never could make it work quite right.

 

[SquareRoot]

2 step solution:

Step 1: place QuadraJUNK into a rockcrusher......

Step 2: get a HOLLEY.......

Problem solved....

Step 3: Place Holley carb in same rockcrusher....

Step 4: get Edelbrock Pro-Flo 4. All problems solved...

 

[broketiredugly]

1000 cfm on a choked port small block chevy? roflmao. and folks complain about the carter afb bogging. lol

 

[Paladin]

Step 3: Place Holley carb in same rockcrusher....

Step 4: get Edelbrock Pro-Flo 4. All problems solved...

My mistake. I was under the impression he was trying to fix the problem, not make it worse!!

 

[Matt69olds]

Good Lord!! The Q-Jet was used for how many years, on how many millions of cars and trucks, and people think they are junk??? If they were really as bad as people make them out to be, then the highways would have been clogged with stalled, flooded, smoking vehicles when these cars were new.

The problem is most people “rebuild” carbs with worn out parts. The best overhaul kit is useless if the throttle shafts leak air, the idle tubes are plugged with 50 years of crud, and the parts in cheap rebuild kits from AutoZone/ advance auto aren’t compatible with today’s fuels. How many people have have rebuilt carbs that work great for awhile, then have accelerator pumps leak or stick? Today’s fuels attack the rubber in cheap kits.

These carbs were expected to start easily everyday, in any weather, perform well, idle smooth, provide decent economy, decent acceleration, restart easy after a hot soak, and above all be reliable. There is no reason a properly rebuilt and tuned Q-Jet can’t do the same today.

People who say they are junk either don’t have the knowledge to work with them, are too lazy to tune them correctly, too cheap to use quality parts, or just refuse to accept they are the most precise and efficient carb ever designed.

 

[SirRobyn0]

Good Lord!! The Q-Jet was used for how many years, on how many millions of cars and trucks, and people think they are junk??? If they were really as bad as people make them out to be, then the highways would have been clogged with stalled, flooded, smoking vehicles when these cars were new.

The problem is most people “rebuild” carbs with worn out parts. The best overhaul kit is useless if the throttle shafts leak air, the idle tubes are plugged with 50 years of crud, and the parts in cheap rebuild kits from AutoZone/ advance auto aren’t compatible with today’s fuels. How many people have have rebuilt carbs that work great for awhile, then have accelerator pumps leak or stick? Today’s fuels attack the rubber in cheap kits.

These carbs were expected to start easily everyday, in any weather, perform well, idle smooth, provide decent economy, decent acceleration, restart easy after a hot soak, and above all be reliable. There is no reason a properly rebuilt and tuned Q-Jet can’t do the same today.

People who say they are junk either don’t have the knowledge to work with them, are too lazy to tune them correctly, too cheap to use quality parts, or just refuse to accept they are the most precise and efficient carb ever designed.

I think a lot of it is misunderstanding the Q-jet, it's a relatively complicated carburetor compared to say the edelbrock. I think it's also common for folks with less carb experience not to understand how to get the internal passages truly clean.

 

[Blue Ox]

I think a lot of it is misunderstanding the Q-jet, it's a relatively complicated carburetor compared to say the edelbrock. I think it's also common for folks with less carb experience not to understand how to get the internal passages truly clean.

Probably true. Not that the Q-jet is all that complicated, but people don't take the time to understand it. It really only has two inherent issues. The well plugs, and the throttle shaft bores. And throttle shaft thing can happen to any carburetor. It seems like most of the issues are caused by people fiddling with things they don't understand.

They're actually a brilliant piece of engineering for most street and stock vehicles. Finding tuning parts is what limits them for high performance use. But otherwise you'd be hard pressed to find a more efficient and responsive design for most vehicles. Some Ford 429 CobraJets even sported Rochester Quadrajets under the air cleaner housing. If Ford was willing to put them on their high-performance engines I think that says a lot for the "Slobberjet."

But haters are gonna hate.

 

[broketiredugly]

the reason they got the name quadrajunk is because they were not a very robust carburetor. and most of the time were tossed in the junk because the masses thought they would not take a rebuild. the reason they thought this is because the needle taper wore on one side, and the welch plugs leaked down. we woul polish the needle taper, and seal the welch plugs, completely clean the ant holes, and make them work.......till they wore the needels again, and wore the shaft bushings. so, no, they were not a great carb, the 2 bbl rochester was a great carb, the motorcraft / autolite 2 bl and 4 bbl were the very best carbs ever built. afb and thermoquads were the butt of all lead sled jokes and lopar. 429 cobra jet? they were cammed so hard, a quadrajunk would have been the very worse you could run. they sudffered at low end. a 302 would pull em out of the hole. not doubting there may have been a q-jet of two on a 429 fe, but it must have been in a truck motor? maybe 428 i would be more likely to believe. in either case, it wasnt all that. no spreadbore was ever all that. a 350 chevy with a quadrajet in a van was a mediocre engine that sucked lots of gas because the 4bbl was all in as the van turned into a flying brick.
a 350 single exhaust with a 2bbl rochester was an excellent design, made within 10 hp, got tons more mpg and would still idle smooth long after the quadrajunk and the engine it sat on were worn out.

 

[HotRodPC]

the reason they got the name quadrajunk is because they were not a very robust carburetor. and most of the time were tossed in the junk because the masses thought they would not take a rebuild. the reason they thought this is because the needle taper wore on one side, and the welch plugs leaked down. we woul polish the needle taper, and seal the welch plugs, completely clean the ant holes, and make them work.......till they wore the needels again, and wore the shaft bushings. so, no, they were not a great carb, the 2 bbl rochester was a great carb, the motorcraft / autolite 2 bl and 4 bbl were the very best carbs ever built. afb and thermoquads were the butt of all lead sled jokes and lopar. 429 cobra jet? they were cammed so hard, a quadrajunk would have been the very worse you could run. they sudffered at low end. a 302 would pull em out of the hole. not doubting there may have been a q-jet of two on a 429 fe, but it must have been in a truck motor? maybe 428 i would be more likely to believe. in either case, it wasnt all that. no spreadbore was ever all that. a 350 chevy with a quadrajet in a van was a mediocre engine that sucked lots of gas because the 4bbl was all in as the van turned into a flying brick.
a 350 single exhaust with a 2bbl rochester was an excellent design, made within 10 hp, got tons more mpg and would still idle smooth long after the quadrajunk and the engine it sat on were worn out.

You can also hog out a 2bbl Rochester and they perform almost as well as a Qjet. We had a street racer bud named 2 barrel Bill. He was kickin' ass and taking names. He got all the good races cuz everyone just knew they could beat him. Nope. He'd whip their ass. He dialed in his biggo cam to where you could hardly tell he had a big cam in it. Then recurve the dizzy advance, gasket port the intake runners and head ports. It was a running muhfugger. He did end up sneaking some NOS under the intake that noone seen too. How do you get a 2bbl in the high 12's? NOS. A wet NOS set up at that. It was a plumbing beauty under the intake.

 

[Blue Ox]

1970 Torino 429 Cobra Jet and 1971 Mustang 429 Cobra Jet.

Trucks.

 

[thecantaloupeman]

You can also hog out a 2bbl Rochester and they perform almost as well as a Qjet. We had a street racer bud named 2 barrel Bill. He was kickin' ass and taking names. He got all the good races cuz everyone just knew they could beat him. Nope. He'd whip their ass. He dialed in his biggo cam to where you could hardly tell he had a big cam in it. Then recurve the dizzy advance, gasket port the intake runners and head ports. It was a running muhfugger. He did end up sneaking some NOS under the intake that noone seen too. How do you get a 2bbl in the high 12's? NOS. A wet NOS set up at that. It was a plumbing beauty under the intake.

LMAO sounds fun!

I did figure out my choke seems to be working properly. I do have to replace that c clip so the rod doesn't disconnect again. I have no idea how long that was disconnected so I basically never had the choke open up that whole time. Once i fix that hopefully some of my cold start issues are solved. Choke could probably use adjusting but I am not really sure how to do that yet.

Still need to check out float. I might pull air horn again later to take a look.