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Thermoquad question

Posted By: Anonymous

Thermoquad question - 03/04/09 12:39 AM

hey guys, came over from the slantsix.org site. Upsizing my B Body to a '72 340 automatic.

there is a thermoquad 9203s available on ebay. manual says that model was for a 79-80 345 auto/IHC


will this carb work well on my 340?

thanks so much for your input

Keni
Posted By: RapidRobert

Re: Thermoquad question - 03/04/09 12:51 AM

welcome here. I'd contact demonsizzler on this site
Posted By: landon1

Re: Thermoquad question - 03/04/09 01:01 AM

i don't think you want that carb...you should try to get a 71 or 72 carb (pre-smog emissions) or try and hunt down a superquad (aftermarket TQ)- that's the route i was going to try, because of the electric choke feature, then you don't need the correct intake
Posted By: DaytonaTurbo

Re: Thermoquad question - 03/04/09 01:56 AM

If you want to find one you can rebuild yourself and run, find one of the 6000 series, ie the first number is a 6, the other 3 are anything else. The 9000 series are the smogger carbs, which would need some rejetting and other mods before being good to use.

The Vaanth Thermoquad Guide has all the numbers you need to see:

http://members.shaw.ca/crussel/thermoquad/tqguide.html
Posted By: Rug_Trucker

Re: Thermoquad question - 03/04/09 03:11 AM

That carb is for the International Harvester 345 engine. I may actually have one of those. It won't work linkage wise on a Mopar.

I'll be up early tomorrow. Give me a call.

BTW you don't want a '71 model 340 carb.
Posted By: ademon

Re: Thermoquad question - 03/04/09 07:31 AM

Why not a 71 T-quad? thats what most of the F.A.S.T. 71 sb cars are running.
Posted By: Rug_Trucker

Re: Thermoquad question - 03/04/09 01:26 PM

Quote:

Why not a 71 T-quad? thats what most of the F.A.S.T. 71 sb cars are running.




They require different jets and metering rods. They are an air metered carb VS solid fuel. I think I saw repopped Strip Kits for them for $500

Do the FAST cars have to run #'s matching carbs?

Any year TQ can be made to scream. Even the 9000 series OE carbs.
Posted By: MY340

Re: Thermoquad question - 03/04/09 11:20 PM

Quote:

If you want to find one you can rebuild yourself and run, find one of the 6000 series, ie the first number is a 6, the other 3 are anything else. The 9000 series are the smogger carbs, which would need some rejetting and other mods before being good to use.

The Vaanth Thermoquad Guide has all the numbers you need to see:

http://members.shaw.ca/crussel/thermoquad/tqguide.html




Not all 9000 series carbs are "smogger carbs". I ran a #9023 on my built 340. I would recommend using a 72-74 TQ carb. A SB or BB TQ carb will work well on a 340. Just make sure it's jetted right for your application and has a good set of performance metering rods like 1966's.

You can get other TQ's to work well but someone like Demonsizzler would probably have to modify or tweak it.
Posted By: cdp

Re: Thermoquad question - 03/04/09 11:26 PM

The FAST guys are running the special 2-3 year only Competition Series that looks like a 71 carb. The are expensive, rare, and not recommended for the street at all.
Posted By: cudaman1969

Re: Thermoquad question - 03/05/09 02:35 AM

71 carbs are not the way to go, hard to find, and backwards from 72 and up. 72 to 74 or 75 where the best because of the fuel inlet pos. and not all the add on emmision crap. the trap door is the secret to making these work right. there where to types, get the larger front barrels,440 cars, jury rig a choke and keep working with the rods and plunger springs, depends on the vacuum at idle,i.e. cam, good luck
Posted By: dOrk !

Re: Thermoquad question - 03/05/09 05:57 AM

Quote:



the trap door is the secret to making these work right.






The TRAP DOOR ? ... now that is a NEW TERM that most have not heard of !! .... Would that be the secondary air valve ? ... well do I have the TOOL for you ! ..... and it is new and improved from the OEM piece.

That is a major consideration ... but there is a little more to be concerned with than just that.
Posted By: CJK440

Re: Thermoquad question - 03/05/09 02:17 PM

Quote:

The FAST guys are running the special 2-3 year only Competition Series that looks like a 71 carb. The are expensive, rare, and not recommended for the street at all.




Really??

The Comp series TQ's are not legal for F.A.S.T. and if I remember correctly has some pretty significant visual differences too.

Come to think of it, there are very few of us TQ racers.

For the record I'm running a 1973 spec TQ that was remanned by Holley that I bought from Summit.
Posted By: ScottSmith_Harms

Re: Thermoquad question - 03/05/09 02:24 PM

Quote:

Really??

The Comp series TQ's are not legal for F.A.S.T. and if I remember correctly has some pretty significant visual differences too.





Right, I haven't heard that one either.

But in thinking about it, I do see guys running different TQ part#'s other than what's production line correct for thier cars and nobody seems to give them any flack over it, I don't see why they couldn't use a Comp carb just as easily?

They do have some obvious differences, but most aren't visible with the air cleaner on, where do you draw the line when NEITHER carb is correct?

Posted By: CJK440

Re: Thermoquad question - 03/05/09 02:31 PM

The numbers don't matter in FAST. A 73 340 TQ can be put on a 72 340 car.
Posted By: ScottSmith_Harms

Re: Thermoquad question - 03/05/09 02:44 PM

Right, but it goes beyond the numbers. A 72 TQ carb doesn't look like a 71 TQ carb, so what's the difference if a comp TQ also looks different as well? Again, where do you draw the line?
Posted By: CJK440

Re: Thermoquad question - 03/05/09 03:09 PM

I do agree there is some gray area with the way the FAST rules read.

When we revised the rules for Supercars we opened up the carb rule to eliminate confusion. You can run any carb as long as it appears externally similar as the OE peice.

To meet FAST rules I had to take an 800 TQ and machine it to accept 850 throttle plates.

In Supercars I could just go find a similar appearing 850 and plop it on.

The good news for Mopar guys is the cars that left the factory with a 625 with a little cosmetic work, can take advantage of Edelbrocks line of larger AFB's and AVS's and be competitive now in this series.
Posted By: ScottSmith_Harms

Re: Thermoquad question - 03/05/09 03:12 PM

That's my point, that "Gray area" needs some futher work IMO, you can spend allot of money guessing one what you can or can't run. I can make an 850 Comp series TQ look ALLOT like a 71 street version with a little work, only a knowledgable Mopar guy could pick up the differences, and that's only if he's paying attention really close.

So would it be legal?
Posted By: Anonymous

Re: Thermoquad question - 03/09/09 02:40 AM

"If you want to find one you can rebuild yourself and run, find one of the 6000 series, ie the first number is a 6, the other 3 are anything else....
The Vaanth Thermoquad Guide has all the numbers you need to see:"

OK with TQ guide in hand here's what i have found
that I think would work:

-6139S is for a '72 340 automatic
(needs a rebuild).
-6324 is for a 73 HP 440 automatic (newly rebuilt)
-6090 for a 72 400 auto (newly rebuilt)
**4968 Carter AVS for a 71 HP440 auto (newly rebuilt)

will any of these other carbs work well on my 340 ? Will a carb for a 440 HP be too much?

sure appreciate all your feedback. I could talk all day about slant sixs and super sixs. But this muscle world is all new to me!

Keni

Attached picture 5080046-chargersm.jpg
Posted By: 4BBodies

Re: Thermoquad question - 03/09/09 06:04 PM

I rebuilt a 6139S for my '73 340, and I have had to re-work it due to the aggressive cam. It was running lean, I have since added #1966 metering rods and a lighter tree spring. Thanks to Demonsizzler (on this site) it is almost there, (it need jets now) but I wish I had done better homework beforehand. Live and learn. But was it worth it? Yes! It is easily the scariest engine I have rebuilt, it just runs and sounds so nasty, and the TQ is extremely responsive. Ask Demonsizzler his advice on which of the above carbs to use.
Posted By: 4BBodies

Re: Thermoquad question - 03/09/09 06:05 PM

Scary = Fun
Posted By: DaytonaTurbo

Re: Thermoquad question - 03/09/09 06:55 PM

Quote:


OK with TQ guide in hand here's what i have found
that I think would work:

-6139S is for a '72 340 automatic
(needs a rebuild).
-6324 is for a 73 HP 440 automatic (newly rebuilt)
-6090 for a 72 400 auto (newly rebuilt)
**4968 Carter AVS for a 71 HP440 auto (newly rebuilt)

will any of these other carbs work well on my 340 ? Will a carb for a 440 HP be too much?





The 440 and 400 carb will be the same, maybe with a little different jetting stock. The link should say which jets are in there. But any of them will work with some time spent tuning.
Posted By: RoadRunnerLuva

Re: Thermoquad question - 03/09/09 07:02 PM

Kenicb: Go to Demonsizzler's website:
www.thermoquads.com for some good info...
Posted By: Rug_Trucker

Re: Thermoquad question - 03/10/09 04:47 AM

You don't need to worry about over carbing with the 850's.

Hotroddave40 got 29.5mpg in his super mileage 318 Cuda with an 850.

Get the "biggie sized" TQ to start with! The TQ will only pull what the engine demands from it.

What I would like to see is how to mod the emission carbs. How to mod the spray bars etc.

I really want to bolt a 318 model TQ on a hot slant6.
Posted By: CJK440

Re: Thermoquad question - 03/10/09 12:53 PM

Quote:

You don't need to worry about over carbing with the 850's.

Hotroddave40 got 29.5mpg in his super mileage 318 Cuda with an 850.

Get the "biggie sized" TQ to start with! The TQ will only pull what the engine demands from it.




The 800 and 850 TQ's have the same size secondary butterflies. The difference is in the primaries.

Me thinks a small motor street motor that sees a lot of around the town driving would want the 800 for the better vacuum signal where it matters for drivability.

Even the small TQ at 800cfm is huge for a stock stroke small block.
Posted By: Rug_Trucker

Re: Thermoquad question - 03/10/09 10:57 PM

Quote:

Quote:

You don't need to worry about over carbing with the 850's.

Hotroddave40 got 29.5mpg in his super mileage 318 Cuda with an 850.

Get the "biggie sized" TQ to start with! The TQ will only pull what the engine demands from it.




The 800 and 850 TQ's have the same size secondary butterflies. The difference is in the primaries.

Me thinks a small motor street motor that sees a lot of around the town driving would want the 800 for the better vacuum signal where it matters for drivability.

Even the small TQ at 800cfm is huge for a stock stroke small block.




One difference between a Holley and a TQ or Qjet is the AIR VALVES They alter the air flow so you can't over carb with the spring tension set right.

I've ridden in Daves 318 powered Cuda there is no bog with the 850. The primaries are small on the 850's compared to AFB's and Holleys.

1 1/2" on the 850. 1 3/8" on the 800. A BBD for a 318 or super6 has 1 /14".

On my heavy van with a broken air door spring it would lay down and bog. New spring it gets up and honks! Why? The spring regualtes the air flow to engine demand.

Some 360's came with the 850 from the factory.


Posted By: CJK440

Re: Thermoquad question - 03/10/09 11:57 PM

Yeah I'm familiar with the air door but that only regulates the secondaries and there is lots of throttle movement between idle and when the secondaries crack. Till then the air door does nothing.

Perhaps the 1.5" primaries are still small for a stock smallblock, I'm just sayin'.
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