Thermoquad ID

-
G

gzig5

Well-Known Member
Joined
May 3, 2018
Messages
2,837
Reaction score
3,813
Location
Mequon, WI
Can anyone give me an idea what size (CFM) this carb is and/or what model? The seller is local, I haven't seen it in person yet but want to know what I will be working with should I choose to buy it. Looks like some sort of aftermarket or commercial version? They say there are no numbers stamped on the base plate. Thus far communication has not been their strong suit.

6033_n.jpg?_nc_cat=107&ccb=1-3&_nc_sid=843cd7&_nc_ohc=kEhVu86DDrcAX9hPBQg&_nc_ht=scontent-ort2-2.jpg
 
That's one of the competition series. Made in 69 and 70. It's either 850 or 1000 CFM. I wouldn't buy **** without communication. Parts are hard to find for them anyway.
 
Competition Series! 850 or 1,000 CFM. Cool find. Those are from '69-'70-71 I believe. Different metering system (solid fuel) than later production models, similar to early 340 TQs.

It's going to be one of these numbers; ("A" is for automatic) Look on the left front pad where the bolt hole is.

4846S
4846SA
4847S
4847SA

Go here, all the info you will need. A Carter Thermo-Quad Guide
 
I thought it might be a Competition but the ones I've seen had that on the label. I can't see it in the pic I have.
He said it has 1.5" primary and 2.25" secondaries.

I'm familiar with that site. Wonder why it states the following? "The Competition Series carbs should generally be avoided except for racing."
 
gzig5 said:
I thought it might be a Competition but the ones I've seen had that on the label. I can't see it in the pic I have.
He said it has 1.5" primary and 2.25" secondaries.

I'm familiar with that site. Wonder why it states the following? "The Competition Series carbs should generally be avoided except for racing."
Click to expand...
"The Competition Series carbs should generally be avoided except for racing".......................That's like saying to a guy, "Don't use this cam unless you want to go really fast!!!":rofl::rofl::steering:
 
The reason is the primaries are ether a zero venturi or a minor reduction for a minor venturi from what I am told. This would make them not the best on the street since there is no venturi.

Mine is not even stamped with a number.
 
No reason you can't run it on the street but tuning/rebuild parts are really hard to come by because there's basically none left on earth. Also, if this one has press in jets its a royal PITA to change them. Street driving is mostly low rpm/part throttle operation which is where regular solid fuel TQs shine. Plus, the parts availability is much broader. Still a cool carb though, I'd like to run one for the wow factor.

There's a guy on Ebay who has been trying to sell a few NOS TQ Comp. Series Strip Kits for years now with no buyers because he wants $500 for them.

Carter 10-110 Strip Kit Thermo-Quad 4972 4973 Metering Rods Needle & Seats Jets | eBay

Informative thread here;
[FOR SALE] - COMPETITION THERMOQUAD 850cfm
 
rmchrgr said:
No reason you can't run it on the street but tuning/rebuild parts are really hard to come by because there's basically none left on earth. Also, if this one has press in jets its a royal PITA to change them. Street driving is mostly low rpm/part throttle operation which is where regular solid fuel TQs shine. Plus, the parts availability is much broader. Still a cool carb though, I'd like to run one for the wow factor.

There's a guy on Ebay who has been trying to sell a few NOS TQ Comp. Series Strip Kits for years now with no buyers because he wants $500 for them.

Carter 10-110 Strip Kit Thermo-Quad 4972 4973 Metering Rods Needle & Seats Jets | eBay

Informative thread here;
[FOR SALE] - COMPETITION THERMOQUAD 850cfm
Click to expand...
Yeah, I love TQ's, but the cost of those strip kits is ridiculous. Unlike the AVS2 I am currently running; most TQ's I've run needed to be tuned with different jets/rods. Boy, when they're right, they're right though!
 
What is in the strip kits? jets, rods and springs?
Jets and rods aren't too hard to make. Springs can be specced if you can get originals to work from. Maybe I'll look into reproducing them when I retire in a couple years.
 
gzig5 said:
What is in the strip kits? jets, rods and springs?
Jets and rods aren't too hard to make. Springs can be specced if you can get originals to work from. Maybe I'll look into reproducing them when I retire in a couple years.
Click to expand...
Yes, jets, rods, springs and other small parts.
You can reproduce these?
What do you do for a living and how soon do you retire?
 
Excellent find & exc carb!!!!!

Both the 850 & 1000 cfm models have the same pri & sec bores. To tell the difference: the 850 carb has the extra booster ring in the primary venturiis like the production TQs; the 1000 does not.

The Carb Shop in Eldon Missouri had kits for these, & I think Woodruff carbs has them also.

Push in jets are NOT a problem. Get some AFB/AVS piston springs. Open up the top two coils so that they fit over the jets. This will stop the jets from falling out. Spring length may need trimming; you want the springs to touch the float bowl floor.
 
rumblefish360 said:
Yes, jets, rods, springs and other small parts.
You can reproduce these?
What do you do for a living and how soon do you retire?
Click to expand...
I'm an engineer for a large industrial automation company. I can currently make small quantities of various things but any kind of volume production would depend on whether I convert my manual machines to CNC and what the process needs are. I'm not interested in spending my retirement turning handles all day.
QuadrajetParts.com lists TQ jets, rods, and about everything else for them if anyone is currently looking for something.
 
@gzig5
I'm not interested in spending my retirement turning handles all day.
Click to expand...
Amen to that!
Do you have your own home equipment?
That would be cool as heck.
 
I've been rebuilding manual mills and lathes for about fifteen years. I clean them up, re-scrape the way surfaces if needed and get them running and cutting well and put them to use making parts for the next project. Occasionally sell one to fund the next. I rarely repaint them, I like the used look. I've been meaning to convert to CNC but just never commit to it. I don't have a big shop, just a 2 1/2 car garage and the wife's parking spot is non-negotiable, so I stuffed everything into my half. When I got my 73 Cuda I had to clear space in the garage for it and ended up selling my Rockwell tool/surface grinder, Sheldon horizontal mill, 2500lb Rockwell 14 x 40" lathe, two South Bend Heavy 10 lathes, a small Rhodes metal shaper, and my big Miller Dialarc 250 HF TIG. I got to admit that was a tough decision to get rid of my babies, but the car couldn't live outside. Currently I've got a 1939 Index vertical mill with a TREE head on it and various grinders/sanders/Hyd press/welders/tool boxes in the garage. It is TIGHT in there. In the basement I keep my EMCO Super 11 lathe with mill head and a couple smaller lathes. Working on cars and old machinery keeps me out of the bars and keeps me distracted so I don't drive the family nutz.
 
Maybe you might be the one guy who should pick up that carb and see what you can do with it!

I for one would sure like to see someone make metering rods at home. Jets I can see, probably a 3 operation lathe job? Chuck the stock in the jaws, whittle it down to size, drill out the orifices, cut some threads if needed and then put them in the mill for the screwdriver slot but the metering rods - not so sure how you would do that? Seems like a more finite operation with the steps/taper and then the bend on the top. Would you bend the top first?
 
I've turned small shafts before and even with razor sharp tooling, deflection is an issue. Need a live support in the tailstock and/or a follower rest. It might work best to use a tool post grinder after roughing them to size. Minimal stick out from the chuck and really high spindle speed. Bending would be the last step.

The jets are pretty straight forward, just small and not much to hold onto when cut off to work on the other end. In my mind the steps are: I'd rough turn the diameters, center drill the tip, drill/ream the passage, thread the end, cut off, cut the slot and then back in a collet to do the counterbore on the top. Lots of steps and tool changes. I couldn't sell them for $10/pair if it was all done on a manual machine. A small turret lathe would help speed the manual process. A Swiss screw machine could spit them out pretty quickly. Even though I work cheaply for myself, you need CNC production capability to make enough parts quickly to sell at a reasonable price.
 
the rods can be center less ground, expensive but that would be the way to do it. I believe that originally they were roll formed. you would have to make a die to bend the top to get the length all the same rod to rod. as for the jets, if you were to cut the threaded end first, it could be screwed into a threaded hole held in the lathe chuck. not sure how much concentricity matters from one end to the other but within a couple of grand would be close enough I would think.
 
you haven't answered how much he wants for it, but if its less than a couple hundred dollars buy it no matter what.
 
I picked it up yesterday afternoon and I'll just say that I probably paid below market price on it, whatever that may be.
It seems to be an 850 with the double booster ring on the primary. No part numbers stamped on the base. Seems to be in pretty good shape, but I'm sure it needs clean up and rebuild. I guess I'll have to take the top off to figure out the jet situation and figure out what kit it takes. Guy said he had it on a 70 Challenger with a stout 440. Blew the engine then sold the car and the carb has sat on the shelf for 27 years.
 
If you’re willing it would be cool if you document the rebuild and of you decide to make parts that would be amazing. Don’t get to see the insides of those things too often.
 
You must log in or register to reply here.
-

Back
Top