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  #1  
Old 07-18-2006, 02:00 AM
Bigshot Bigshot is offline
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Default About the Thermoquad carbs.

Ok so if I'm not mistaken the thermorquad carb on my 440 appears to have a layer of plastic in it.. Every car guy I know has told me these are garbage carbs and I should just get rid of it..

But around here on moparchat they seem to be a good thing.. Unless the guy I bought it from was wrong when he said it is a thermoquad, what is going on here? Are they good or junk?

PS. My 440 is a stock 1975, out of a new yorker bouraghm(sp?)
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  #2  
Old 07-18-2006, 02:31 AM
72Challenger 72Challenger is offline
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The body is made of plastic, so that part sounds right. That's also why they tend to have a bad reputation - the plastic has been known to warp and cause all kinds of problems. But when one is working right, it's hard to beat for a street setup. It has excellent throttle response and can give good mileage if you keep your foot out of it most of the time. It is also easier to tune than a Holley. Racers have been successful with them as well, although the spreadbore design can cause fuel distribution problems.

That said, I use a Holley myself, but my car, even though built for the street, is more on the racing side of the fence.

DWC will be along soon to tell you more about how this carb is the best design ever built, everyone should have one, it can cure cancer, and bring about world peace.

(Hi DW! )
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  #3  
Old 07-18-2006, 02:51 AM
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Not sure it can cure cancer, but it brings my Mopar world peace for sure.

And it is the best carb ever made as long as you don't need anyhting over 1000 cfm and then you have to use two of them. The carb uses a phenolic resin bowl. Same thing the dist. cap is made of. Lot of people say they warp, but I have yet to run across one that is warped. I have run across them that were broke when hit by something. Some times the jet well covers will leak, but that's an easy fix with some new epoxy and it's nothing to turn you away from using one. It does not happen that often.

The prim uses two booster rings and a smaller prim than the holley or any other cab. That alone makes it more throttle responsive than any other carb. And then the sec. come on and it meters the fuel as needed. Never seen a fuel dist. problem while using one. The proper intake and spacers are needed too.

It's the only carb we use on both our race cars and street cars. Only time oyu wont find one on our race cars is when the rules wont allow it. Great carb, so don't turn it down.
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Old 07-18-2006, 03:33 AM
TK TK is offline
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Good carb, but they do warp.
I don't like them, because they warp, and are spreadbores, I like my cylinders to be getting the same amount of fuel, that is hard enough with a dual plane intake, let alone a spreadbore on top................

Now, for my fun.

Quote:
And it is possibly the best carb ever made as long as you don't need anyhting over 1000 cfm, or a square bore. If you need more than 1000cfm, smoke some crack, and use two of them. The carb uses a phenolic resin bowl. Same thing that cracking, brittle, dist. cap is made of. Lot of people say they warp, and they are right. I have also run across them that were broke when hit by something like a paper towel, or a feather. Usually the jet well covers will leak, but that's an easy fix with a big blob of some new epoxy and it's nothing to turn you away from using one. It does happen often.

The prim uses two booster rings and a smaller prim than the holley or any other cab, besides a quadrajet, and a 500CFM AFB. That alone makes it more throttle responsive than most other carbs. And then the sec. come on and it meters the fuel as needed. Never seen a fuel dist. problem while using one because I am color blind, and cant see the difference between tan, brown, and white. The proper intake and spacers are needed too.

I am so hard headed, It's the only carb we use on both our race cars and street cars. Only time oyu wont find one on our race cars is when the rules wont allow it, or we have gotten sick of the rear cylinders running lean. Great carb, so don't turn it down.
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  #5  
Old 07-18-2006, 10:01 AM
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rumblefish360 rumblefish360 is offline
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The bowls do warp. I have one warped now. They also crack after many thermo cycles. I have one of those now. You can get them new for $75. Not a big deal. Rebuild kits are $38. Click here; http://thermoquads.com/

There not junk. They are tricky when your not used to them. I like them. I also like the Holley double pumpers, not the vaccum secondarys. I like the AVS carter, not to keen on the AFB carter.

Fuel distibution is not an end all and it's a small problem. It happens more so when the secondarys open up early and fuel dosen't stay in suspension well and/or dumps fuel in.

There bad rep is from years ago that was part of a multi part problem.
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  #6  
Old 07-18-2006, 12:42 PM
DEMON SIZZLER DEMON SIZZLER is offline
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It is certain that everyone has their favorite when you talk carbs. No other engine or car part raises such a controversy as the discussion of carbs does.

The truth is, a carb has so many variables to it that selection at some point, is crucial to the overall performance of the engine. Too large or small a carb and tuning becomes difficult if not impossible. And a carb is not properly tuned until all three circuits(idle, main and hi speed)are properly dialed-in.

Which is a better carb, a Holley or an Edelbrock, a ThermoQuad or a Q Jet? This is a matter of opinion and a matter of what you prefer and which carb you are most familiar with. I happen to like ThermoQuads more for several reasons: first, these are oem carbs, so the metering is closer as is compaired to other styles of 4 bbl carbs like a 3310 Holley or Performer carbs. The good news is that plenty of tuning parts are available for the Holley and Edelbrock carbs and ThermoQuad and Q-jet carbs. You will improve gas mileage with a T.Q. over some of the other 4 bbl carbs. ThermoQuad carbs flow alot of cfm's but meter gas/air extremely well but only what the engine demands in cfm's. It is tue that the main bodies will warp and the main jet wells will leak but it is far more likely that the wells will leak than the main body will warp. Every style of carb has design short comings for sure, just be aware of these before you make a final selection. Tunability is important and the more you can read about each carb style, the better you will be able to make the right decision on carb selection. In my opinion, with the proper selection, spending the needed time to properly tune your carb and knowing how to diagnose carb problems, any one of these 4 bbl carbs will work well, David.
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  #7  
Old 07-18-2006, 03:03 PM
John Kunkel John Kunkel is offline
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Quote:
Originally Posted by DEMON SIZZLER
It is certain that everyone has their favorite when you talk carbs. No other engine or car part raises such a controversy as the discussion of carbs does.

Which is a better carb, a Holley or an Edelbrock, a ThermoQuad or a Q Jet? This is a matter of opinion and a matter of what you prefer and which carb you are most familiar with.
A much more creditable answer than "it is the best carb ever made".
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  #8  
Old 07-18-2006, 03:25 PM
custom880 custom880 is offline
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Around my MOPAR circles they are always referred to as Thermo-Junk. I have had a few as OEM carbs on 70's cars. Most times they were good carbs but they do have some problems. If you know them and know the problems and the little tricks with them they can work just as good as a Holley, or Carter, or Stromberg, so on and so forth. All carbs have their problems, none of them are perfect.
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  #9  
Old 07-18-2006, 03:29 PM
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1973Swinger 1973Swinger is offline
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Wow, now that was about the best post about carbs that I have seen on here. Very nicely said Demon Sizzler!

Personally I like Holleys, but I dont have any real experience with TQs, mainly Q-jets, Holleys and Edelbrocks, and out of those 3 I have had the best luck with Holleys. I have seen all of them work very well though when tuned right.
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  #10  
Old 07-18-2006, 07:18 PM
Bigshot Bigshot is offline
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Well I'll take a look into my TQ and see if it is worth rebuilding.. $40 seems a lot better then $700 etc..

I know for sure right now the carb is not useable, not sure what the problem is as I've only had my 440 running once, when it was in the car it was pulled from. I know after less than 15 minutes of running, we shut it down, and there was steam/smoke/vapors coming from the carb...

Anyways I'd like to add to you guys that I'm a complete amateur to this hobby but I think I'm learning fairly easy. So I may ask a lot of questions and need fairly detailed answers.
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  #11  
Old 07-18-2006, 08:38 PM
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Go ahead and ask. Most of us can set you in the right direction. And that's what we are here for.
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  #12  
Old 07-19-2006, 03:09 PM
Tarrbabe Tarrbabe is offline
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Default I got here much too late.........

I would have told him they were junk and to get a Holley. And of course since there are restrictions on how these carbs can be disposed of, he could send it to me since I'm an approved ( by me ) processer for salvage thermoquads. Then I could have sent it to Demonsizzler and had it TUNED up. I need another carb for my truck. Opps, shouldn't have said that I guess.
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  #13  
Old 07-19-2006, 03:35 PM
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rumblefish360 rumblefish360 is offline
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(What Tarrababe said....Ha ha ha ha ha

Thats one reason I keep messing with OE carbs. Cheap cheap cheap cheap to play with.
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  #14  
Old 07-21-2006, 09:08 PM
gthomas gthomas is offline
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I still am using the original TQ that came on my car when it was new. It still works fine. No warping and no problems so far. I've always been very careful when tightening it down on the manifold, and thats where I believe most people go wrong and cause warping because they don't eveningly and slowly torque it down.
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