What could I do with this Thermoquad?

[halfafish]

I know a guy getting rid of a Thermoquad for peanuts. It's a 9190S model, which references to a '78 440, Medium Duty, Auto Trans, California carb. It appears to be complete and all the linkages and shafts move freely. It also comes with an incomplete 9036S carb that might be good for parts if needed. I also have a scabby 9117S I can use for parts. Certainly, the 9190S would need a rebuild as it's been sitting for a long time. It is a smogger carb, for what that's worth.

I hear a lot of talk that a good running TQ is a thing of beauty. What would this be good for? I have no BB aspirations so this would likely go on a moderately beefed up 318 or maybe my 340.

And to complicate matters, I am a Carb Goon. They are kryptonite to me but I'd give this a go if it looks like it would work on one of my engine.

TIA, and fire away!

 

[Demonx2]

Toss it in a lake? Or give to me for spare parts?

 

[rumblefish360]

‘78 is a tough year to decipher. Pictures of the vacuum tubes?
Less the better. EGR port? Purge? Charcoal canister port? In the primaries, the front wall, are there a port in each leading to the outside air?

It’s possible to get it to work but the earlier ones are better and easier.

Any of these top 4 you stumble across or non emission TQ from a car or truck is what you want. The less vacuum hook ups the better. Up front, 3 vacuum tubes at most. On the back, there is one for the secondary pull and at the max, 1 more for straigh full time vacuum. No main bowl EGR port. The port on the top is a vent tube port and that’s OK to have. You also want the fuel inlet to be on an angle, not straight up and down.

4846S	Competition Series	331	341	615	1-1/2	8
4846SA	Competition Series	3080	3116	615	1-1/2	8
4847S	Competition Series	331	341	616	1-1/2	8
4847SA	Competition Series	3089	3116	616	1-1/2	8
4972	71 340 MT (3512820)	3074	3125	655	1-3/

 

[rumblefish360]

Perhaps this cheat and descriptions can help.

Port Diagram​

This section contains a diagram and notes to identify the various hose port connections on the Thermo-Quad. Different port configurations were used throughout the years. The diagram is a representation of the throttle base, top view. It is drawn with all possible ports. The label notes identify the ports and their general usage. Some ports are contained in the bowl or bowl cover. These are also identified. The ports are labeled by (x)...descriptions follow the diagram.

(A) Distributor Vacuum Advance (black, 71-75, some 76-84), 5/32".

• (B) Idle Enrichment (IE) (gold, 75-81 some models), 5/32".
• (C) PCV (gold, 71-84), 11/32". * Note:: angled on 80-84 models.
• (D) Canister Purge (ECS) (red, 73-82),, 1/4".
• (E) EGR (gold) or Air Pump (blue), 5/332".
• (F) EGR venturi port (brass), 1/8", {located on phenolic float bowl}.
• (G) Bowl Vent (gold, 71-77), 11/32", ((located on the upper bowl cover}.
• (H) Air Cleaner Heated Air Temp Sensor (black, 78-84), 5/32".
• (I) Power Brake Tube (gold, 81-84), 111/32".
• (J) Air Cleaner Heated Air Temp Sensor (black 71-77), 5/32", Bowl Vent Solenoid Vacuum Tube (gold 78-84), 5/32".
• (K) Canister Bowl Vent Tube (gold, 78--84), 11/32".
• (L) Choke Pull-off (gold, 71-84), 5/322".
• (M) Choke Pull-off Diaphragm (natural,, 71-84), 5/32", {bolts to TQ base}
• some other vacuum attachments were used, ie. secondary pull-off and vacuum throttle positioner...these (like item M) were external to the TQ.

 

[rumblefish360]

Go here for the source and a good chart to see;

A Carter Thermo-Quad Guide

 

[ch1ll]

Good of you fish for providing all that info. I’d stick to the 74 and down TQ’s. Don’t even mess with the lean burn or California carbs. Not too hot on the altitude compensator carbs as well unless you live in the mountains. The 71 is big money carb. Will work well on the street. The competition series are race carbs only as the boosters are one ring only. May not give you the throttle response you want on the street. Best of the bunch are the 9800 series carbs that were sold through direct connection but some of them are for Chevy linkage so you have to read the model numbers carefully.

The 9190 and others I would not waste my time with.

 

[ch1ll]

You have to be careful mix and match different carbs cause like the article says, circuitry was changed through the years.

 

[lemondana]

Try to piece together the 9036, it's a 74-75 440 truck carb. The truck carbs had minimum emissions stuff on them, good ones to use.

 

[Brooks James]

9190 HD, it could be a non lean burn heavy truck carb, if it is I will visibly have less ports for emissions hoses, and will be jetted/rods richer than a passenger carb mixture.
I've had several 360 HD truck carbs that fit that bill, that worked great on lightly modified 360's

 

[rumblefish360]

Good of you fish for providing all that info. I’d stick to the 74 and down TQ’s. Don’t even mess with the lean burn or California carbs. Not too hot on the altitude compensator carbs as well unless you live in the mountains. The 71 is big money carb. Will work well on the street. The competition series are race carbs only as the boosters are one ring only. May not give you the throttle response you want on the street. Best of the bunch are the 9800 series carbs that were sold through direct connection but some of them are for Chevy linkage so you have to read the model numbers carefully.

The 9190 and others I would not waste my time with.

Thanks @ch1ll

There are two 1 ring and two dual ring competition TQ’s. The larger being listed as a 1.000 cfm and the other an 850 cfm.

There are 4 models of the electric choke TQ. All are small primary. There is a MoPar and Chevy variant. Each came with and without an EGR port.

I have used a Chevy arm TQ with good results on a ‘78 - 400B engine. The swap to a larger primary TQ improved throttle response and power very noticeably. The small primary TQ was used on a 340 for a year or two or three….. I forget…. Then it was replaced by the larger primary TQ. Which is favorable for any type of usage.

The small primary TQ is best used on a low powered 360, a stock 340 is OK, excellent on the 318. On a 318, it will perform great for a mileage seeker or a street strip build

You have to be careful mix and match different carbs cause like the article says, circuitry was changed through the years.

Oh yea! The phenolic resin bowls have an easy 4 different models, there not so readily interchangeable.

9190 HD, it could be a non lean burn heavy truck carb, if it is I will visibly have less ports for emissions hoses, and will be jetted/rods richer than a passenger carb mixture.
I've had several 360 HD truck carbs that fit that bill, that worked great on lightly modified 360's

Exactly! Some of the truck carbs do not have all the vacuum hook ups. Trucks were exempt in many states, so the carbs, even later years are good to go.

 

[ch1ll]

My bad on the one ring booster comp TQ. I only have one comp TQ and that is the one I have. I assume that is the 1000 cfm model?

Never thought about the trucks not having emission equipment and I believe you are right.

 

[Bewy]

I have been using & tuning TQ carbs for decades. Once all the emission ports are blocked off on the later 9000 series models, I noticed no difference in performance with the earlier 6000 series which had less emission ports.
800 cfm models had 1.375" pri throttle bores & these would be preferable on a stock or near stock 318.

The larger 850 carbs have 1.5" pri bores & would be good on a 340. The secondaries on each size are the same, so really only talking about the difference in the primaries. And the difference in actual operation is not that great. [ GM used QJs with the small 1.375" primaries on all their big block engines, except for just a few models].

 

[Bewy]

Another thing to remember is that only race engines would use the total cfm capacity of these carbs, & then probably not that many. A 340 engine that has say, a longer duration cam, but still streetable, has peak hp at 5800 rpm with 85% VE only needs about 500 cfm of carb air flow.

 

[rumblefish360]

My bad on the one ring booster comp TQ. I only have one comp TQ and that is the one I have. I assume that is the 1000 cfm model?

I thought the same until someone here posted up differently. It was a dual ring race TQ. These carbs are not seen everyday. I would assume you have the 1,000 unit.

Never thought about the trucks not having emission equipment and I believe you are right.

Cali maybe different on this. IDK. Bewy mentions plugging up the vacuum ports. The ones inside the primary barrels (if equipped) should also be handled. I had one such TQ. I could t get it to go very well. It was a long time ago, so, I don’t know what I missed.
Swapped to another TQ and it was good.

That experience had me thinking it may have been the carb. Or more so something about the year of the carb. This MAY not have been the case. Having a number of them at the time, I just decided it was easier to try another carb rather than pull my hair out trying to make it work.

 

[Dartswinger70]

Rebuild it and document it here every step with pics let us know how it works so then I have something to go by rebuilding mine...? I need info on how to reseal the wells...

 

[halfafish]

‘78 is a tough year to decipher. Pictures of the vacuum tubes?
Less the better. EGR port? Purge? Charcoal canister port? In the primaries, the front wall, are there a port in each leading to the outside air?

Thanks Rumble, I did read up on the article on TQ's. This carb is full of ports - here are some photos.

Try to piece together the 9036, it's a 74-75 440 truck carb. The truck carbs had minimum emissions stuff on them, good ones to use.

Not a bad idea, I'll see if the linkages and whatnot will swap over. I have nothing to lose in this deal so I may just try it to see if it works.

 

[Ceedawg]

Get it for parts if cheap enough. Ports can be plugged real easy. Everything is in the base so middle can be used again also the 440 carbs had bigger primary’s

 

[rumblefish360]

Thanks Rumble, I did read up on the article on TQ's. This carb is full of ports - here are some photos.

View attachment 1716128593

View attachment 1716128595

Yep, emissions era carb loaded up pretty good. Idle compensator included. Very good for traveling up and down the mountains.

Not a bad idea, I'll see if the linkages and whatnot will swap over. I have nothing to lose in this deal so I may just try it to see if it works.

Pay attention to the fuel bowls and the top gasket used.
Not all are able to be swapped.