Lets discuss thermoquads

pigpen

pigpen

Tugging my johnson while
I'm trying to decide if I want to run a 650 holley or the factory style thermoquad.
I like the concept of the small primary's sipping fuel and the sound they make when the secondaries pop open. On the down side is the only experience I have with them is taking them off and tossing 'em.
Any certain part numbers I should keep an eye out for? Certain ones that are just trash?
It's for a very mild 360. Thanks
 
I would run a Thermo.....in fact, between the ones I gave Orvil and the ones I still have, I am sure we could find you a re-build candidate! :)
 
I liked those Thermo's and got really good at rebuilding, tuning and maintaining them.

But then I got lazy and just bought Eddy's. :shifty:


They are a good carb and pretty easy to set up provided you picked the right one for the job.
 
Last edited:
don't forget to put 150 lbs of return spring on it if the throttle shaft bushings aren't already fried. between me and my brother there is a stack of 10 or 15 and yup they all whistle dixie. most are smoggers but there are a few "cool" ones.

someone:huh: is selling bushings that you have to drill for,, need to get busy.
 
T-quads are great carbs if rebuilt properly. They only have a bad rep because most people don’t understand how to build and tune the properly. I’ll dig up some numbers for you, just give me a chance to track down my info.
 
Piggy,

You may recall that I went through essentially the same decision making process when I bought my 360 duster. I decided to try and make the thermoquad work, and I'm glad I did. There is a guy who has a company that deals only in thermoquads as far as I know. The web address of his company is: [url]http://www.thermoquads.com/[/URL]

Mine has the bushing whistle and still runs pretty well. I will probably send it off to him to have it rebuilt correctly. In short, I would advise trying the thermoquad.
 
Thanks all! I guess I'll need to find one that flows like a stock 72/ 73 340 carb.

I'll look into that web site you posted V8440. Thanks again.
 
I may be wrong on this, but my understanding is that absolutely every thermoquad made is 800 cfm or more. Smallblocks got 800's and big blocks got 850's. Then there were some 1000's made years ago, though I know much less about those. The main thing isn't to find the biggest one you can lay your hands on, but to find one old enough that it's not an emissions model. I think they started getting crapified in 1975, but I've also read that they can be de-crapified to produce one as good as the early ones made before the crapification started.
 
As long as it's got no wiring and has a vacuum-advance port, it's worth a try. If it has only one wire, it's still decent--that's for the bowl-vent solenoid. Hook it to a switched (ignition) 12V+ and you'll be fine.

For a mild 360, any of the later 400/440 carbs is a good candidate, right down to the factory jetting.

As far as flow goes, there are two sizes of factory ThermoQuad: 800 and 850. There are 800 big-block carbs and 850 small-block units. It all depends on application. Avoid the "solid fuel" 1971 carbs at all costs. The 1000CFM unit is an aftermarket race carb (Competition Series" is plainly cast into the top plate in a raised rectangle), and is expensive to purchase. You don't need it.

The only people that trash TQs are those who can't figure 'em out. On a street car, I'd have nothing else. Good economy, great performance when you want it, and since the dense chuck 'em, tuning parts (jets and rods) are only as far as the guys giving them away. Maximum performance: Holley, period. Anything else, give me a TQ. Lacking that, I'll take an original AVS or a Quadra-Jet anytime over any Edelbrock or AFB.

One more thing: having owned 70+ Mopars plus having lived la vida eBay, I've owned well over 100 ThermoQuads. Other than one I got from beeper*71 that was damaged in a fire (I knew that going in), I've never had one with throttle-shaft problems. Ever. The only problem I've encountered was damaged main bodies (the phenolic part), be they cracked or warped, and missing parts.

Get a good TQ and never look back.
 
Dr.Jass said:
As long as it's got no wiring and has a vacuum-advance port, it's worth a try. If it has only one wire, it's still decent--that's for the bowl-vent solenoid. Hook it to a switched (ignition) 12V+ and you'll be fine.

For a mild 360, any of the later 400/440 carbs is a good candidate, right down to the factory jetting.

As far as flow goes, there are two sizes of factory ThermoQuad: 800 and 850. There are 800 big-block carbs and 850 small-block units. It all depends on application. Avoid the "solid fuel" 1971 carbs at all costs. The 1000CFM unit is an aftermarket race carb (Competition Series" is plainly cast into the top plate in a raised rectangle), and is expensive to purchase. You don't need it.

The only people that trash TQs are those who can't figure 'em out. On a street car, I'd have nothing else. Good economy, great performance when you want it, and since the dense chuck 'em, tuning parts (jets and rods) are only as far as the guys giving them away. Maximum performance: Holley, period. Anything else, give me a TQ. Lacking that, I'll take an original AVS or a Quadra-Jet anytime over any Edelbrock or AFB.

One more thing: having owned 70+ Mopars plus having lived la vida eBay, I've owned well over 100 ThermoQuads. Other than one I got from beeper*71 that was damaged in a fire (I knew that going in), I've never had one with throttle-shaft problems. Ever. The only problem I've encountered was damaged main bodies (the phenolic part), be they cracked or warped, and missing parts.

Get a good TQ and never look back.
Click to expand...

Yup what he said.....:p
 
every one out this way i ever came across has had a warped cracked or broken plastic body.......sooo ive NEVER seen a "good" one lol
 
I quit looking for a good one a long time ago, it's too easy to find original AVS's. :huh:
 
You can mill up to .011 of the top of a warped float section and have no problems.

If you fallow the rebuild procedure in the F.S.M. to the “T” and make all of the linkage adjustments as described you will have a fantastic carb.
 
69.5CUDA said:
every one out this way i ever came across has had a warped cracked or broken plastic body.......sooo ive NEVER seen a "good" one lol
Click to expand...
Dude, what do you people do out there? Drop trees on them? Like I posted previously, I've had over 100 of these carbs, and only one plastic main body has been bad... and that one had been in a fire.

No offense, but methinks you're blaming a component for your own lack of ability to make it work. That's not an insult, OK? But people don't spend enough time learning to make the damned things work and therefore pass them off as junk because they put an AFB on there and it runs better out of the gate.

68R/T: ThermoQuads are about 1/4 the price of factory AVS carbs, out-perform them, and provide better fuel economy when your foot's not in it. I like the original AVS, but the TQ is a better value all around.
 
none taken doc..after about 20 carbs i gave up looking...there an intresting carb but i never found one that was any good..most were warped pretty badly..so once ya pulled em off out at the wrecker and got em home pull it apart for a cleanup only to try and assemble it and find it warped all to hell or a internal crack ro so warped you cant mount em

im sure there a good carb ..the one on the 73 340 cuda was so so..it was by far the BEST one ive seen and it had a hairline crack
 
Dr.Jass said:
ThermoQuads are about 1/4 the price of factory AVS carbs, ....
Click to expand...

Everthing I've owned from the muscle era has been of the pre-70's. Therefore all were square-bore carbs.

The only spread-bore carbs I've ever owned was one on a 69 Eldo which was a sweet runner, and the other was on a chev 305. But that whole motor was junk. :doh:
 
I just ordered a dual plane manifold for my w2 motor, and I'm hoping to god that it will accept a spreadbore carburetor so I can put a thermoquad on it. The site didn't provide a picture of that particular manifold part number so I can't be sure. The thing is, I HAVE to run that manifold, as it's the only one for w2 oval port heads that's a dual plane.
 
Why on earth would you want a duel plane intake? Are you planning to pull a trailer with a W-2 engine?
 
I'm building a sleeper 4 door valiant. It's not gonna have a bunch of gear or converter, and I want the engine to look stock. I have no need for the extended rpm range a single plane would probably give me. This engine ought to produce awesome midrange power for its size with very good low end torque too.
 
You must log in or register to reply here.

SiteLock

SiteLock
Back
Top