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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Adam71Charger]
#2041256
03/29/16 03:35 PM
03/29/16 03:35 PM
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Joined: Jul 2011
Posts: 819
Eugene, Oregon
Secret Chimp
super stock
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super stock
Joined: Jul 2011
Posts: 819
Eugene, Oregon
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I just swapped on a Street Demon 625 for my old Qjet yesterday. There is a difference, but not a night and day difference. The Qjet shares concepts with the TQ (I really prefer working with the Qjet over the TQ after having messed with both, though).
I took the time to rebush the primaries and get mine dialed in as best I could, and for a 40 year old carb it worked worlds better than the Carters I tried on the motor before. Started in any weather, good economy, no bogs (tighten the door spring and the pull-off pot so it doesn't start dumping open early, NBD).
Doug Roe's book is a good reference and QuadrajetParts.com was where I preferred to get parts from (nothing against Cliff Ruggles, QJParts just has more selection). If you can come into one for cheap or free that has the adjustable APT, it's worth your time messing with if you're coming from an older Holley or Carter design. If you can just as easily drop $200-300 on a newer-design carb, at the very least you're paying for brand-new and updated systems proven by Qjets and TQs, which isn't necessarily a bad thing.
1967 Dodge Coronet Deluxe station wagon
1.03" T-bars, QA1 arms/rods, Cordoba/GM Metric/Volare brake & knuckle, XHDs, Hellwig rear sway, 318 Magnum w/ air gap, 727, 3.23s
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Adam71Charger]
#2041313
03/29/16 05:09 PM
03/29/16 05:09 PM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Decent running when clean. The small built in fuel filter can get clogged, then it bypasses and lets garbage in the carb, usually sticking the needle/seat and flooding the carb. I put a in-line fuel filter in the fuel line before the carb unless it needs to look stock.
I think someone else mentioned the single needle/seat assembly will limit the amount of fuel that can be supplied to the carb in high HP applications.
The Thermoquad can have issues with warpage and cracking of the main body. Also, on either, you need to check the plugs used to seal the passeges because they can become loose and leak.
Last edited by 451Mopar; 03/29/16 05:17 PM.
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Adam71Charger]
#2041492
03/29/16 09:41 PM
03/29/16 09:41 PM
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Joined: Jan 2003
Posts: 42,714
Spokane Washington
ScottSmith_Harms
Mr Wizzard
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Mr Wizzard
Joined: Jan 2003
Posts: 42,714
Spokane Washington
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The Thermoquad can have issues with warpage and cracking of the main body
The "Warpage & Cracking" problems with Thermo-Quads is almost mythical yet I have yet to see one come through my shop that was actually warped or cracked from normal use. The broken ones I have seen (and I've only seen a few) were almost ALWAYS caused by someone trying to pry one apart before all the bolts were removed.
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Adam71Charger]
#2041580
03/29/16 11:03 PM
03/29/16 11:03 PM
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Joined: Jan 2003
Posts: 8,550
Highland, MI.
Sunroofcuda
master
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master
Joined: Jan 2003
Posts: 8,550
Highland, MI.
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Back in the 80's & into the early 90's we bought a lot of GTO's out West, & brought them back to MI. to sell. Also a lot of Mopars & an occasional few Fords. Even a '73 Javelin once. All I can tell you about the Quatrajet carbs, is when a GTO would sit for a week or longer, the carb went dry & the car would not start. You'd have to prime them every time. A Mopar or anything else could sit for a month, & you could get in it & start it right up. That's all I know about Quadrajets.
No Man With A Good Car Needs To Be Justified
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Adam71Charger]
#2041647
03/30/16 12:26 AM
03/30/16 12:26 AM
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Joined: Oct 2003
Posts: 3,386
KY USA
mopargem
master
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master
Joined: Oct 2003
Posts: 3,386
KY USA
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Back when I had General Moronics products 30 years ago, I loved the sound of the QJ's secondaries kickin in.
68 Polara 500...LL1 Y7 M6X
69 Hemi road runner...X9 X9 M6X
69 A12 road runner....R4 R4 M6X
69 ModTop FLORAL Super Bee...F6 M6W
70 AAR 'cuda...EW1 EW1 H4X9
71 Duster 340...FJ6 V24 L6X9
71 road runner FC7 V1X M6X9
72 Rallye Charger B5 V1W
74 'cuda 360...KB5 V1X A6X9
08 SRT Challenger #234
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: mopargem]
#2041800
03/30/16 10:26 AM
03/30/16 10:26 AM
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Joined: Sep 2003
Posts: 20,742
north of coder
moparx
Buying your homeless and unwanted bolt on battery terminals
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Buying your homeless and unwanted bolt on battery terminals
Joined: Sep 2003
Posts: 20,742
north of coder
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"quadrajunks" got their bad reputation when a friend of my brothers and his "expert mechanic" [many,many years ago] worked on the carb that was on his 71 or 72 buick. later that afternoon, my brother's pal showed up complaining now his car really didn't run any better after his "expert" tuned it, in fact it ran a ton worse ! well it didn't take any time at all to discover the "expert" put the top on with the metering rods attached. it seems upon tightening everything up, the metering rods were kinda "pretzel" shaped.  a few minutes with pliers, screwdriver adjustments, and a slight timing change [all with use of a vacuum gage], and "geegooollie !" that tank NEVER ran that good ! this still brings up chuckles today when mentioned. to my brother's buddy, not so much !  
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: mopargem]
#2042148
03/30/16 05:26 PM
03/30/16 05:26 PM
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Joined: Jan 2003
Posts: 8,550
Highland, MI.
Sunroofcuda
master
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master
Joined: Jan 2003
Posts: 8,550
Highland, MI.
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Back when I had General Moronics products 30 years ago, I loved the sound of the QJ's secondaries kickin in. Sound as good as a Thermoquad when the secondaries kick in? That's an awesome sound!
No Man With A Good Car Needs To Be Justified
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: 383man]
#2042421
03/31/16 12:03 AM
03/31/16 12:03 AM
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Joined: Jan 2003
Posts: 8,550
Highland, MI.
Sunroofcuda
master
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master
Joined: Jan 2003
Posts: 8,550
Highland, MI.
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A carb story I always get a personal chuckle out of is a '72 Cuda 340 I bought off a local guy that "never ran right." This was back in 1985 & the car was a beautiful, all 100% original paint totally rust free car, with a rebuilt 340 with a warmer cam & 202 heads, & the guy that owned it was a Mopar guy from way back. His good buddy was a Chrysler engineer & they both mused over what the problem with the sluggish Cuda was for several years. They theorized that the engine had the wrong cam. Anyway, I caught wind of the car going up for sale & went & bought it.
After a couple of weeks, I decided to look at the carb - a Thermoquad. I could swear the secondaries were not opening - you couldn't hear them. I removed the carb & the first thing that struck me as odd was the secondaries were all carboned-up - just black looking in there. I soon discovered that the secondaries were NOT opening, & tweaked a linkage elbow on the RH side of the carb til they opened every time when the throttle was moved to WOT. I reinstalled the carb & went for a ride. It's like I added 100 HP. A week later I met up with the Chrysler engineer guy while out cruising on a Sat. night. I told him to jump in & took him for a ride. He was estatic: "WHAT DID YOU DO?" I told him about the secondaries.............you could have heard a pin drop.
Last edited by Sunroofcuda; 03/31/16 12:03 AM.
No Man With A Good Car Needs To Be Justified
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Sunroofcuda]
#2042459
03/31/16 12:51 AM
03/31/16 12:51 AM
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Joined: Jan 2003
Posts: 27,421
Balt. Md
383man
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 27,421
Balt. Md
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A carb story I always get a personal chuckle out of is a '72 Cuda 340 I bought off a local guy that "never ran right." This was back in 1985 & the car was a beautiful, all 100% original paint totally rust free car, with a rebuilt 340 with a warmer cam & 202 heads, & the guy that owned it was a Mopar guy from way back. His good buddy was a Chrysler engineer & they both mused over what the problem with the sluggish Cuda was for several years. They theorized that the engine had the wrong cam. Anyway, I caught wind of the car going up for sale & went & bought it.
After a couple of weeks, I decided to look at the carb - a Thermoquad. I could swear the secondaries were not opening - you couldn't hear them. I removed the carb & the first thing that struck me as odd was the secondaries were all carboned-up - just black looking in there. I soon discovered that the secondaries were NOT opening, & tweaked a linkage elbow on the RH side of the carb til they opened every time when the throttle was moved to WOT. I reinstalled the carb & went for a ride. It's like I added 100 HP. A week later I met up with the Chrysler engineer guy while out cruising on a Sat. night. I told him to jump in & took him for a ride. He was estatic: "WHAT DID YOU DO?" I told him about the secondaries.............you could have heard a pin drop. I can imagine how much better it felt as it was running on just the small primaries ! When them big secondaries kick in it sounds like it wants to suck the hood in. Cool story.  Ron
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Re: Why do Quadrajet carbs have such a bad reputation?
[Re: Sunroofcuda]
#2042468
03/31/16 01:07 AM
03/31/16 01:07 AM
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Joined: Feb 2003
Posts: 10,386
Someplace you aren't
SomeCarGuy
I Live Here
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I Live Here
Joined: Feb 2003
Posts: 10,386
Someplace you aren't
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Back when I had General Moronics products 30 years ago, I loved the sound of the QJ's secondaries kickin in. Sound as good as a Thermoquad when the secondaries kick in? That's an awesome sound! The qjets ive driven are in no way cooler than the t quads when mashed.
I want my fair share
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