Thermoquad vs Holley - losing hair -Help!!

[hotrodsouth]

Guys,
I just put an original intake manifold and Thermoquad carb on my stock '71 340 Challenger RT 4spd, and I can't get it to run correctly. The manifold and TQ carb are both the correct model number for the 4spd application and the TQ had a high-dollar professional "concourse" restoration to factory specs. The car runs extremely rich, stumbles from a stop, lurches when coasting down from speed (before pushing in the clutch). When you start the car cold (80+ degrees down here in TX) you have to push on the gas to keep the engine at 1500 RPM or it stalls. I tried advancing the timing, which helped a little, but far from fixing the probem. During the warmup, it runs terrible with eye watering (rich) fumes coming out the exhaust. once it's up to operating temp, it idles about 1200 RPM, if i adjust to idle screw even the smallest amount, it drops to 300 RPM (nothing in between). Yesterday I got fed up, pulled the TQ, and put a spreadbore to square adapter on with a Holley 600 vac secondary that I had sitting around the garage. The car ran great (just a little rich). So here's my question...I wanted an all original setup and hate the look of the adapter plate. Any ideas on getting the TQ to work right or should I spend another $400 on a Holley spreadbore (designed for the GM's) and try that?...I hate to spend more money if I can get the TQ to work...the $well is running dry. I'm pulling my hair out on this one. help...Thanks!!!

 

[74CudaDave]

I'm guessing something went wrong during the "concourse" restoration. I've got a Holley 750 vac sec on my 440, and I've experienced many of the same issues you're talking about, and it always boils down to something I've done wrong or mis-adjusted. It's always something simple. I'd say you need to take the TQ back off and go through it again - find a good manual/rebuild book and tear into it, carbs aren't that bad once you wrap your brain around them.

 

[Rob C]

Who did your reto work on the carb.

That carb needs to be set up as per factor specs at every bend/rod/flap etc....
The rods may not be correct, even if they are, todays gas isn't the same as it was 30 - 40 years ago. You may need to find a thicker rod to lean it out. Re adjust the pump shot arm.

Finallly, I find nothing wrong in the use of a Holley over a factory carb. Sometimes, it just works for ya. The Spreadbore Holley I never really liked. You'll need about a 5/15 of an inch rise to bolt on a typical square bore carb to clear the TQ intake choke well or EGR valve. If so equiped.

 

[hotrodsouth]

Thanks

Thanks for the input. I'm going to try and figure out the Thermoquad. I'm think there must be something not set right on it. If anyone else has any thoughts or knows of a website dedicated to tuning a thermoquad, please let me know. Thanks again.

 

[hotrodsouth]

Carburetor restoration by Pony

Pony Carburetors in New Mexico restored the carburetor...it cost about $500 for a "concourse plated restoration". I will keep posting my progress here. The restoration was in 2007 and was paid for by the former owner of the car and was never installed until I tried a couple weeks ago.

 

[burntorange70]

Could there be a crack in the plastic part of the TQ? Just a thought. Kind of sounds like a vacuum leak.

 

[hotrodsouth]

Good thought...It does seem like a vacuum leak. I have the TQ on the workbench now checking every part of it for a problem. I'm going to be distracted with my job the next week or so, so I won't have much time to mess with this, but I will post my progress and maybe some pictures when I get a chance. Thanks for the ideas guys.

 

[Cranky]

This guy is good on the TQ http://thermoquads.com/ but they are not hard to work on once you learn them. I went through a learning curve with my 71 340 Cuda too. It ran nice when I got it but after a rebuild many years later, I went through my 'learnin' lol but once I figured it out, my 17 mpg in town mileage came back and it still ran a 14.0 at the track!

 

[Big Jim]

Get your TQ lined out yet? Biggest thing to remember is that EVERYTHING is interconnected- change the adjustment for one thing and it changes something else.
Even so, I much prefer the driveability of the TQ over a Holley (always thought "Holley" was nice way to say hammer practice...LOL)

 

[mopartim]

I just did the same thing with my '72 Challenger. I had the original 6139s and intake laying around but the plastic float bowl had a big hole in it. Took me a few swap meets to find one and put it back together. Now it's not perfect yet, but it now gets better mileage and more WOT. The trade-off is a little less mid-range, but is worth it to me. I was running a Holley 750 before.

 

[Chryco Psycho]

tuning is tougher , It is hard to get Jet kits squirters for them,
Like any carb they have good & bad points

 

[Cuda360]

hotrodsouth, I don't mean to usurp your thread but my quandary is somewhat similar. I need a new/rebuilt carb and I'm unsure as to whether I should get a new Holley or have my TQ rebuilt. The shop to which I went said they could get me an already rebuilt TQ for $550, this includes giving up my current one as a core. This brings up a new question, Are all TQs the same? If I give up my 74 TQ, how do I know the one I get back is the same and not one from, say, 78, or 70 for that matter? Any advice will be appreciated.

 

[Chryco Psycho]

f it was my $$ I would get a new Proform 750
far more adjustable & all the parts to tune it are available unlike the TQ
but if you want the stock look ...
Your call

 

[burntorange70]

There should be a # on the side of the TQ. It will tell you year and motor. Do a google for TQ ID and you should fnd a list with all the # on it.

 

[VeteranCosmicRocker]

hotrodsouth, I don't mean to usurp your thread but my quandary is somewhat similar. I need a new/rebuilt carb and I'm unsure as to whether I should get a new Holley or have my TQ rebuilt. The shop to which I went said they could get me an already rebuilt TQ for $550, this includes giving up my current one as a core. This brings up a new question, Are all TQs the same? If I give up my 74 TQ, how do I know the one I get back is the same and not one from, say, 78, or 70 for that matter? Any advice will be appreciated.

No, they are not all the same. Just like other carbs, you have to look at the number as the other poster stated. These are very good carbs & easy to rebuild/tune, but if the plastic composite body is warped, it's done. You have to disassemble it & check that first, just like a block deck or head.

 

[Rob C]

Holley re manufactures TQ carbs. Check out summit racing for them. Maybe cheaper. Though I can not say anything about there quality. Others have complained. This is a carb you can rebuild yourself. There is a book on Carter carb'sand it shows how to do all 4 carter 4 bbl. carbs.

 

[Chryco Psycho]

You have to check over the bowls very carefully on the TQ , they not only warp but crack & the wells can come loose or leak if the epoxy gives up

 

[Cudafever]

there is a guy by the name of demonsizzles that i have heard a lot of good about..................................................................

Hmm looks like that link above was him, but not on the net any more???????

here is a phone # if you want to see if he is still in bussiness.

Phone Number: 770-498-8776
Web Address: thermoquads.com
Contact Name (if applicable): David
Mopar Specialist: Yes

 

[Cudafever]

Phone Number: 770-498-8776
Web Address: thermoquads.com
Contact Name (if applicable): David
Mopar Specialist: Yes
Personal Experience with Vendor

I think he is on the A Body forum "DemonSizzles"

 

[Rob C]

Nope, itis still "Demonsizzler" at the A body forum and other forums.