I really want the Thermoquad sound but should I?

I'm starting to make time to put the Imperial's 440 together. The original plan was to inject it but I think I'm going to go with a carb for a while. That would get me on the road quicker and allow me to use the extra funds for other stuff on the car.
I've been looking at the Street Demon and my CH4B.

The engine is built for low to mid-range torque with 10.2:1 compression, Eddy heads, and a mild cam. The old Desktop Dyno software suggested the build would make 460+ lb/ft from 2000 - 5000 with a peak nudging 500 lb/ft. HP would top out around 440. It's a 5300 lb car with a 3.23 gear and 29" tires.

So, assuming I can turn 400 lb/ft at the wheels to get this fatty cruising effortlessly down the highway, should I do it with a reman TQ and different intake or stick with the Street Demon and CH4B? Sadly, I don't have hood clearance for a Performer RPM or carb spacer.

My first car was a 74 RR with a 360 and I miss the sound of that Thermoquad at full gallop. The Imperial is very quiet and that howl would add that extra little touch that the old beasts need.

You SHOULD ! ... the ticket is actually the smaller cfm card on a Eddy Streetmaster intake

Might as well try the new Street Demon
. It gets great reviews and its design takes the best attributes of the Thermoquad , Quadra jet and AFB and puts it into an all new carburetor.

Hell yeah. Nuttin' sounds better than a thermoquad trying to suck the hood off. Plus, a well tuned thermoquad is a grrrreat carb.

Jack

Agreed mopJack ... bester than a Berri crab any day !

The only one of those new street demons I know of around here don't have the t-quad sound.

I would think a silenced vs unsilenced air cleaner would affect the sound of wide-open secondaries.
I can hear the secondaries on my AVS with the unsilenced type.
I don't recall hearing the T-quad under the silenced dual-snorkle being louder on another car I had some years back.
But that could be a sign of advancing age...

My vote is go with the TQ but ya can't really go by me - I'm running (4) of them. What year Imp are ya working on?

FOUR diff cars ? ... now YOU get a free mEmEbErShIp into the ThermoSquad !

I have nothing directly on point. I did run a 800 cfm Holley spreadbore on the factory manifold on my Charger (4300 lbs, stock converter, 3.23, 915 heads, manifolds, 2 1/4" exhaust, MP 272 0.455" cam) after a fresh stock stroke rebuild and its low end was impressiveness. We took that carb/manifold off my car and put it on my buddies 68 X with a well worn, low compression 440 and it ran great too. Both cars would go sideways in 1st gear, and ran into the 13s at over 100 mph.

If it were me, I would go TQ, and use a regular Performer intake.

Do I get a window sticker with that?

Can I get 5 of them because I've got this other car I'm working on and...

It's a large by huge 72 Imperial crew cab.

Another vote for the Plastic Fantastic.

I ran one on a 429 I had in a 65 F100. It ran like nails. Great on fuel when driven accordingly and hard on Camaros when you didn't.

Kevin

Best of both worlds reasonable mileage when driving easily and performance (and great sound) when getting sporty.

TQ all the way, fantastic carburetor design. Consider this, Chrysler used them from 1971 well into the 1980's on nearly every V8 they sold, they were in direct competition with fuel injection and performed well against it!

T-Quads frigging rule. Find a decent used one & rebuild it. I'm saving an OE cast iron intake for a 440 I might have one day even! Came off a 440-Mag 73-74 Charger I found in a junkyard in AZ. many years ago.

Check out this ..... TQs A PAIR ... and all smiles !

Their is a pic of Grumpy Bill Jenkins and his tunnel rammed dual thermoquad pre 1970 Camaro out there.

As opposed to those tiny coupes?

When it comes to big barges the fuselage ones have always been my faves. 70 ish 300 drop top on the bucket list. TQs really fit the luxo cruiser well - mild and quiet when running on just the primaries, terrifying in a refined and civilized way when you hold them all the way open. Depends on the gear. Later Imps had higher gears and I've driven a couple 74s and 75s that would shift in to 3rd around 80 mph. About the time the passengers start getting uncomfortable about how wound up the big block is and wondering if it will ever shift, it does and they really start to worry because it's still pulling like an aircraft tug.

Agreed, on an automatic car the downshift combined with the T-Quad opening the massive secondaries is an intimidating sound.

Agreed, on an automatic car the downshift combined with the T-Quad opening the massive secondaries is an intimidating sound

Yeah, just ask the Illinois Nazis........

Can you still get TQ's? I used to have a basket full, eventally gave them all away Is there room for dual set up on Weiand intanke on first Gen 392?

You can get remans from Rockauto

An OEM style choke will be an issue though there are electric conversions out there.

Is that the one that is kinda square looking and is like the Thermoquad ?? Also I remember guys turning the air cleaner lid upside down to have about a 1/4" to 1/2" open space around the air cleaner edge as it really woke up that suction sound where it sounded like it wanted to suck the hood into the eng. It was mostly guys with the Quadrajet that did that as there was many more of them around then Thermoquads but the are like the Thermoquad with large secondaries and small primaries. Ron

My 1st V8 car was,,h code 340 with 727. A friend of my brother gout in 95 per cent shape. But slowly ruined it. So 340 727 323 sure grip with rally pack dealer AC was a great car. Ran well with the factory TQ Carb. Screemed with the lid upside down. And g
Had great milage.

O heck. After some "research" I find that smallest CFM on Thermoquad is 800. Too much for my 2 4 set up on my 1st Gen 392, so reckon I am SOL. I had gotten excited about running a Thermoquad (actually 2) again. I know that a single Thermo is better than my 2 500CFM Edbrocks set up, but sometimes you just gotta go with the WOW!!! factor of 2 instead of 1 .

I don't trust reman TQs from anywhere except my bench. Have seen too many of them fouled up and no surprise as they're not exactly easy to set up. Ok, was one guy that did them for years and knew his thing but he's pretty much faded. The last few I build for myself were ebay $50 ish basket cases, some parts from my stash and a few bits from quadrajetparts.com Nice thing about that site is ya can buy the 4 parts you need for 1/3 the cost of a generic rebuild kit with a bunch of parts you don't need.

As far as I know, the CFM rating is what they're capable of inhaling and it only comes in to play when your engine is trying to gulp more than what it can suck through the carb. Basic example is that TQs came in 800 (early) and 850 (most) versions and Chrysler used them as OEM on 318s which clearly wouldn't need all that air. The trick, and the cool thing about TQs, is mix and match rods and jets until you get the net fuel rate that works with your engine.

Leather acc pump from Quadrajet parts works great too.

I wanna try out this combo for fun once I get my new hood. Ive prepped up a pair of #6322 TQs with some tweaks, freshened them up and put in new throttle shaft bushing.

VERY interested to see how they will dial in on the X ram

I've been toying with the idea of running a TQ myself but I don't know if I want the headache. It sounds like getting one of them dialed in is bordering on voodoo, plus you have to scrounge a good used one and hope whoever rebuilds it knows what they're doing.

Thermoquads are not difficult to build at all, in fact, they are quite simple, I have several on my personal cars and build a ton of them. The biggest problems I see with them are when backyard engineers think that they are smarter than the engineers who designed them and start modifying them "To make them better". Bottom line? There is no "Voodoo", you simply need to learn how to adjust one properly which is also easy if you can read a technical manual and follow instructions. No, they are not the same as a Holley, so if that's all a person has ever messed with you'll need to open your mind and learn something new. not a big deal for most people who can turn a wrench. A good place to start is a factory service manual, there is also a good tutorial on the Imperial Club website. Imperial Club Site Link Here

Scott - That is truly a thing of beauty.

I can't say I've often heard TQs described as simple. As for voodoo, that's no help. Perhaps the be best analogy here is women - they make a lot more sense when you understand how they work. I've always said that the linkages connecting the choke, choke pull off, fast idle cam and secondary air door is a design Rube Goldberg would be proud of. The subtitles of It are under documented and your best help there is another correctly set up one for reference. The frequently misunderstood thing is the relationship between curb idle throttle setting, curb idle mix setting and meter rod yoke height. The last one being the most important part of the carbs designed in flexibility and a thing many people screw up and then try to compensate for by screwing up the other adjustments.

Best argument yet

I know of a Ken Manley ( he's on Facepage ) and RWG75 that rebuilds them.

Oh, and ~Yes~ Go for it

Just installed the Street Demon on my 440 and....WOW! Car has never ran better or sounded as good. Quick throttle response and steady RPMs. I can't say enough good things about it. Will never go back to the Edelbrock.

This pic is the same carb pictured above before final assembly. A lot of the rebuilders out there don't take them down this far and leave the throttle shafts in them, and rather than replating the linkage and small parts they paint them to doll them up. When torn down 100% they can look intimidating, and sure, they are different but are really no more complex than other Carter or Holley 4 barrels.

Love it!

Steve Dulcich:

LAD 5241: Did you replace the shaft bushings yourself, or sent it out?

If yourself, can you provide the pertinent part # info and any procedure details? Thanks!

I believe the TQ can be tuned to just about any combination. However, having said that, the more radical you get in the cam selection the harder of a time you are going to have in trying to get the card to respond to the engine vacum signal changes.

My base for this statement: I've been using these things for years and currently run the aftermarket 9800 series (the one with the attached electric choke on the side). It took some work to get the idle mixture screws to actually respond, so literally the engine runs differently as you turn the screws. Previously in my combo (238/244 @0.050 duration hydraulic flat tappet cam) only the idle speed screw did anything. That cam is pulling only about 6-7" of vacum though.

Dave Emanuel's book is a great reference if you are new to these carbs and are going to work on them (ISBN 0-931472-11-3).

I have a nice Carter tech book on this carb, but it's too big to attach, so IM me and we can exchange through email.

Spread bore or EFI, why not both:
Sniper EFI Quadrajet





I'm thinking of going with one of these on the 440 in my wagon, likely on top of a Holley SD intake.

Nice except for the $1800 price with pump and extras.

To youz who like the sounds that Plastic Fantastic producers ... you need that new and improved air valve tool to get the bestest tUnEs !

And it probably don't have that TQ howl

That's an interesting question.

I has always assumed it was a function of the LARGE secondaries. So I wouldn't be surprised if this produced a similar effect...Q-Jets had some of that. But nothing barks quite like a TQ.

Howl ... bark !! ...

Even IF that Sniper EFI delivered any real benefit over a Street Demon, there is no way it can possibly deliver 6 times the benefits over the Street Demon which is how much more it costs. Plus the extra labor.

I have said this before, The only guys that dismiss the Street Demon for our mostly stock and mostly street cars, are guys that haven't tried one.

Or wants the TQ sound.

The AVS2 (650CFM) I just installed on a 383 does a pretty good impersonation of a T-quad's secondaries-open sound.
I'll do a separate thread on it for anyone interested.

One of the things that I dig most about my old stuff is that they're not efi, computer controlled, technology dependant. Sure, there are times when I gotta pop the hood to get one started but I'll take that over wrestling with a smart phone app any day. As for something that sounds like a TQ, I'm thinking the thing that comes closest is a TQ.

Mandatory picture...

I like this one

WHERE are those T shirts ??

I got a dozen or so of these off eBay some years back

[quote LAD 5241: Did you replace the shaft bushings yourself, or sent it out?

If yourself, can you provide the pertinent part # info and any procedure details? Thanks! [/quote]

Yep bought a kit with the ream and the bushes. Disassemble the carb, and you can use the ream in reverse in the drill chuck and the straight shaft on the ream is used as a guide in the throttle bores to enable you to ream it straight and true.

Then loctite the new bushes and drive them in - I used a bolt with the correct OD and the threads cut off to use it as a bush driver.

Worked like a charm

https://www.youtube.com/watch?v=UvHIWqdJX8s

https://www.ebay.com/itm/3-8-Throttle-Shaft-Bushing-repair-Worn-Carburetor-contain-Reamer-16-pcs-Bushing/232906517346?hash=item363a4f6b62:g:JXQAAOSwFSNcAdk3

How much slop was there in that shaft ?

Not huge slop Doc, but it was there; I tested it and it had a whistle at idle that was the shaft for sure.

The shafts themselves were in good shape however.

Throttle shaft slop is not usually a problem unless the carburetor is a high mileage unit or someone used throttle springs with too much pressure causing the bores to become egg-shaped, typically most evident on the driver side. This is why my process includes re-bushed bores with every carb, its a simple procedure to eliminate any potential slop issues.

This is what you don't get with parts store or internet parts store rebuilds. You get the same thing if you just buy a rebuild kit and do your own. You need to see someone like Scott to get a proper job done.

Well right here offy coarse!!!

I had a few cars with "that sound" like in the 75 New Yorker video.

Those same cars with an exhaust upgrade from manifolds and single exhaust to headers and dual exhaust. I remember losing that sound.
It's always had me thinking that a restrictive exhaust makes the Thermoquad have that sound.

Are those TQ TeeSHirts still being sold?

Well that looks pretty simple. Where do you source the screws for attaching the throttle plates to the shafts? Been many moons since I tore one down that far but I recall having a really hard time finding those screws and maybe just ended up using whatever small machine screw that fit.

The above shirts with that logo have never been sold.
"Photoshop"

I made the 'Join the ThermoSquad'-logo a bunch of years ago just for fun. I photoshopped and based it on an image from the cover of a Carter Carburator Tuning book by Dave Emanuel.

BigBlockMopar,

Thanks, though I recognized the picture but never saw a shirt I am making up some shifts soon with carb logos, that's a cool one but I'd use a different carb for mine