Thermoquad questions

[Juan Veldez]

I have two TQ's. One is a 6166S for a 1972 400 Automatic (currently on my car) and the other is a 6321S for a 73 400 HP automatic that has the altitude compensating diaphragm for the vacuum advance. I have a chance to pick up another "parts" carb that is a 9096 which came out of a 1977 440 truck with an automatic. Looking at a TQ guide, it doesn't look like much, if any, of the parts interchange. Agree or disagree?

 

[Challenger RTA]

Agree

Vaanth would be more versed on this matter. But I do agree.​

 

[Vaanth]

I have two TQ's. One is a 6166S for a 1972 400 Automatic (currently on my car) and the other is a 6321S for a 73 400 HP automatic that has the altitude compensating diaphragm for the vacuum advance. I have a chance to pick up another "parts" carb that is a 9096 which came out of a 1977 440 truck with an automatic. Looking at a TQ guide, it doesn't look like much, if any, of the parts interchange. Agree or disagree?

Vaanth would be more versed on this matter. But I do agree.​

The 9096S Thermo-Quad could be a reasonable parts source for many of the parts on a 6166S or 6321S Thermo-Quad carburetor.

The 9096S is one of a few 9XXX numbered carburetors, along with numbers 9014S, 9015S, 9022S, 9023S, 9036S, which retained the 6XXX numbered carburetors' style main body (float bowl) and cover (top) as well as a similar throttle body. Following is a quick listing of parts that could be used for spares directly or somewhat:

Direct fits:

• Floats
• Float pins (9096 may have a different style)
• Choke plate and shaft
• Choke pull-off
• Choke linkages
• Accelerator pump, spring, and check valve
• Discharge tube
• Accelerator pump cluster (squirter) (double check the stamped number)
• Accelerator pump pivot, linkage, S-link
• Bowl vent lever, puck, and spring, plus linkage
• Bowl vent tube
• Inner vent tubes
• Secondary air valve, shaft, pivot, spring, and locknut
• Throttle linkage, secondary lockout lever, and secondary linkage
• Idle screw and spring
• Fast idle screw and spring
• Throttle plates (1-1/2" primary)
• Metering rod and bleed area covers and screws
• Body screws
• Step up piston, spring, and hold-down cover (style may differ) (re-adjustment might be needed)
• Fuel inlet fitting
• Needles and seats
• Idle stop solenoid lever/screw/spring, and solenoid, if used
• Mixture screw springs, but not the mixture screws
• Base gasket(s) and air horn gasket
• Miscellaneous clips, screws, etc.

Somewhat fits:

• Jets and metering rods will interchange but differed in sizing between the carburetors
• Main body numbers are different but the bodies are similar.
• Cover can swap. Casting number should be 6-2146 for a direct swap.
• Throttle bodies can swap but are slightly different. Mixture screw taper at the end changed in 1977. Screws will thread in, but do not interchange functionally

Carburetor kits are the same for 9096S, 6166S, and 6321S.

The foregoing is written with original parts under consideration. Changes from the original that might have occurred can alter things.

NOTE: It was mentioned that your 6321S carburetor has an "altitude compensating diaphragm for the vacuum advance". This carburetor did not originally have an Altitude Compensator (AlComp). AlComp was introduced in 1975 and the top cover is a notably different 9XXX style. Also, AlComp is not involved with distributor vacuum advance. If your 6321S has an AlComp, things have been swapped around onto the throttle body.

 

[Challenger RTA]

A few weeks ago I fired my car up. And it was running a bit rich and rough. Check choke and idle screws. Removed cleaned for debris then reinstall the same turns. They where clean. Everything moving and not hanging up. Checked plugs and wires all good connection. This car came stock with a dual point. Cleaned and checked gap still a little rich. Most rocket scientist think they need to adjust the carburetor. Not this one, I'm not that smart. So I think simple. What did I or didn't I do yet! I know years back. I rebuilt the 2 or 3 TQ's I have and use the ethanol resistant parts. It's getting fuel, air and spark. SPARK! Cap and rotor. Pop the cap and looked. There was corrosion in the cap and a little on the rotor. Cleaned it up and it ran a lot better. There is a little more to this. Of course one can't leave well enough alone. Continued.

 

[Challenger RTA]

Being a rough idle I did my best for the video. The first one was before I cleaned cap and rotor. The 2nd was after. I can still see the primary weeping a bit of fuel when running. But not dripping when off. I don't think that is quit normal. My thoughts are: Are the primary well seals not sealing, float level to high or other. Thinking I'll be taking it apart before it hits the road shortly. Maybe @Vaanth might pick up on they and know.

​

I did a few other things with this incident. I'll be showing later.

 

[Challenger RTA]

I have two TQ's.

Thanks Jaun for kick starting this mule. Not meaning hijack it. But just adding to it. This might be the time and place to ask questions about it here. I know there is an expert here and it's not me.

 

[Vaanth]

Being a rough idle I did my best for the video. The first one was before I cleaned cap and rotor. The 2nd was after. I can still see the primary weeping a bit of fuel when running. But not dripping when off. I don't think that is quit normal. My thoughts are: Are the primary well seals not sealing, float level to high or other. Thinking I'll be taking it apart before it hits the road shortly. Maybe @Vaanth might pick up on they and know.

​

I did a few other things with this incident. I'll be showing later.

That is too much fuel flowing at the nozzle at idle. There are a few possible culprits.

Most likely, the primary throttle plates are open too far. If you have set the idle high to compensate for another issue such as late timing, rough idle due to a radical camshaft,or other idle roughness, the added opening of the throttle plates and subsequent air flow is moving into transition and the high speed circuit causing nozzle flow, or drip. Ensure the carburetor is not stuck on one of the fast idle steps.

With higher idle speeds for emissions, nozzle drip became an issue. Carter tackled nozzle drip with two methods: swept idle air and idle bypass assist. Idle bypass assist appeared in 1975, so your 1973 6319S does not have these. If you have a hefty camshaft with a rough idle, you may need to resort to drilling holes in the primary throttle plates to allow the plates to be lowered back to a more reasonable position and get out of the transition area. Throttle plates open too far also exposes the vacuum advance slot to air flow and starts vacuum pull on the advance canister at the distributor, exacerbating other things. The flow from the plate holes themselves can still trigger, likely lesser, nozzle drip, but things become more workable. Drilling the secondary plates can be done as an alternative to ensure primary plate holes don't cause a different drip. If you drill holes, start with 1/16" and go up as needed.

Because this seemed to start after a period of not having this issue, you may not have the throttle plate issue described in the foregoing. I mention it first because it can be a likely culprit. If not in this case, the information is here if needed later. The fact that cleaning contacts in the ignition secondary circuit helped does reveal that more spark energy is getting to the plugs, burning the, likely over-rich, mixture better in combustion. If an ignition firing issue is still present, it will make isolating the carburetor issue more troublesome, and in itself could cause spurious vacuum and flow signaling that might lead to the nozzle drip, which in turn compounds the rough running from ignition woes, but that could be a stretch.

If it is not throttle plates open too far, following are some other possibilities to check:
- Float(s) setting too high (even if within specification, tweaking might be required)
- Sunken float(s) - saturated nitrophyl or brass with a leak
- Leaky needle and seat at inlet, or trash in the needle and seat
- Fuel pressure too high overpowering needle and seat seal
- Blocked swept idle air ports leading to too much throttle plate opening to set idle
- Incorrect upper main body to cover gasket
- Slightly open secondary throttle plates (maybe)
- Possible air bleed and/or passages issue, although this typically would result in more of a lean running condition, but if at this point in this list, a good cleaning of all internal passages and inspection of internals is likely in order

 

[Challenger RTA]

First off Thank you very much for your response. I is greatly appreciated. I can't believe this response!!! It's like he was there when the engine was machined and built. He can see the nut in shell and the shell!

late timing, rough idle due to a radical camshaft

I don't think so but I do and will have to check it. I do recall A good while back when I did the engine break in I did keep idle up by any means

issue such as late timing, rough idle due to a radical camshaft,

When I was getting the cam. I was talking to an induvial that was versed in the matter of choosing the cam. I was building for durability. They suggested a cam that was just a but different then my build. A little milder. 280-110 60 474 106 zero ( They said to install it straight up) The cam I was looking at wanted a 2° advance key. The one I put in didn't state that. That I remember a decade ago. It always haunted me because I didn't put it in. The block was decked and line bored pretty much stock components. Went 30 over pistons to make sure everything cleaned up. That is with 1.6 rockers the heaver valve springs, rocker shaft offset shims, lash caps, trued connecting rods, head work guides and seats. Then balanced. I was a bit leery about advancing the cam 2°. I clayed the heads and the clearance was very close to spec I think it was 0.03 clearance. I think I have the clay laying in the engine built kit. This might have to be addressed.

carburetor is not stuck on one of the fast idle steps.

That I know is not stuck. It is turned in about 1 turn. I watch that. The idle screws a about 2 turns out now. But there again I have to be sure to check it.

The fact that cleaning contacts in the ignition secondary circuit

That is one of the first things I did. check battery state of charge. checked plugs, wires and found corrosion in the cap and rotor. So I did clean it and it made an improvement. But I didn't have a new cap. So I did the next best thing. Pulled the dual point and dropped in an electronic dizzy that I just cleaned and put light spring in. Much better. But still rich. Then I seen the weeping from the primary's and not dripping when off. The engine fires, not even a full turn. Just static timed.

starts vacuum pull on the advance canister at the distributor,

That I will have to check!

If it is not throttle plates open too far, following are some other possibilities to check:
- Float(s) setting too high (even if within specification, tweaking might be required)
- Sunken float(s) - saturated nitrophyl or brass with a leak When I rebuilt them I got new parts and reused the brass floats. They sent me the wrong ones.
- Leaky needle and seat at inlet, or trash in the needle and seat Have to check that.
- Fuel pressure too high overpowering needle and seat seal There is a carter high volume fuel pump 3/8 line feeding it.
- Blocked swept idle air ports leading to too much throttle plate opening to set idle Have check.
- Incorrect upper main body to cover gasket That I'm going to have to check. I do remember trimming for float clearance.
- Slightly open secondary throttle plates (maybe) Never gave that a thought!
- Possible air bleed and/or passages issue, although this typically would result in more of a lean running condition, but if at this point in this list, a good cleaning of all internal passages and inspection of internals is likely in order Can DO.
The brass floats they sent don't look right!

Once again thanks for you help in this matter.

 

[Juan Veldez]

Thanks Jaun for kick starting this mule. Not meaning hijack it. But just adding to it. This might be the time and place to ask questions about it here. I know there is an expert here and it's not me.

No worries. Everyone is telling me go FI, but I really want to get a TQ to work and all this will help me in this process also. Cheers - John (real name). For all of you that didn't know, I took that name because I am always the first one up making coffee. Cheers again.

 

[Challenger RTA]

I am always the first one up making coffee

I need that mule kick in the morning. A few of them!

 

[Challenger RTA]

Went back and found a video of it after break in. No idle problems, dripping or weeping. No misses idle rock steady at about 850-900 rpms. It's a short clip of the video. I pause it and can see it all good.
It's been a few years since. I always run the carb dry so there are no issues. Well I think that might be the issue. Might have pulled some debris in to the needle and seat. There is a filter in it but that's not fool proof. While in there I check a few other things. Also rest idle mixture and timing when done. So really just maintenance! It's a fine balancing act in sequence. If I don't know. I will find a pro that does know! A Thanks to Vaanth. He got the wheels tuning.

 

[Vaanth]

First off Thank you very much for your response. I is greatly appreciated. I can't believe this response!!! It's like he was there when the engine was machined and built. He can see the nut in shell and the shell!

I don't think so but I do and will have to check it. I do recall A good while back when I did the engine break in I did keep idle up by any means

When I was getting the cam. I was talking to an induvial that was versed in the matter of choosing the cam. I was building for durability. They suggested a cam that was just a but different then my build. A little milder. 280-110 60 474 106 zero ( They said to install it straight up) The cam I was looking at wanted a 2° advance key. The one I put in didn't state that. That I remember a decade ago. It always haunted me because I didn't put it in. The block was decked and line bored pretty much stock components. Went 30 over pistons to make sure everything cleaned up. That is with 1.6 rockers the heaver valve springs, rocker shaft offset shims, lash caps, trued connecting rods, head work guides and seats. Then balanced. I was a bit leery about advancing the cam 2°. I clayed the heads and the clearance was very close to spec I think it was 0.03 clearance. I think I have the clay laying in the engine built kit. This might have to be addressed.

That I know is not stuck. It is turned in about 1 turn. I watch that. The idle screws a about 2 turns out now. But there again I have to be sure to check it.

That is one of the first things I did. check battery state of charge. checked plugs, wires and found corrosion in the cap and rotor. So I did clean it and it made an improvement. But I didn't have a new cap. So I did the next best thing. Pulled the dual point and dropped in an electronic dizzy that I just cleaned and put light spring in. Much better. But still rich. Then I seen the weeping from the primary's and not dripping when off. The engine fires, not even a full turn. Just static timed.

That I will have to check!

If it is not throttle plates open too far, following are some other possibilities to check:
- Float(s) setting too high (even if within specification, tweaking might be required)
- Sunken float(s) - saturated nitrophyl or brass with a leak When I rebuilt them I got new parts and reused the brass floats. They sent me the wrong ones.
- Leaky needle and seat at inlet, or trash in the needle and seat Have to check that.
- Fuel pressure too high overpowering needle and seat seal There is a carter high volume fuel pump 3/8 line feeding it.
- Blocked swept idle air ports leading to too much throttle plate opening to set idle Have check.
- Incorrect upper main body to cover gasket That I'm going to have to check.
- Slightly open secondary throttle plates (maybe) Never gave that a thought!
- Possible air bleed and/or passages issue, although this typically would result in more of a lean running condition, but if at this point in this list, a good cleaning of all internal passages and inspection of internals is likely in order Can DO.
The brass floats they sent don't look right!
View attachment 136967
Once again thanks for you help in this matter.

Went back and found a video of it after brake in. No idle problems, dripping or weeping. No misses idle rock steady at about 850-900 rpms. It's a short clip of the video. I pause it and can see it all good.
It's been a few years since. I always run the carb dry so there are no issues. Well I think that might be the issue. Might have pulled some debris it to the needle and seat. There is a filter in it but that's not fool proof. While in there I check a few other things. Also rest idle mixture and timing when done. So really just maintenance! It's a fine balancing act in sequence. If I don't know. I will find a pro that does know! A Thanks to Vaanth. He got the wheels tuning.

It sounds like you have a plan. Having the before video and the after video is good. Narrow down any intended changes that might have occurred in between, and if none that has an effect on this, look for the unintended change(s). It may just be deterioration due to debris or float height shift or other contaminants inside.

Regarding the floats that you pictured. That is a later revised aftermarket version of the brass float:

The following image shows the original Carter brass float and a nitrophyl float:

The newer brass float will function in place of the Carter floats, but check for any gasket interference. The height setting and method for the later brass is a little different than the original brass. The later brass float setting is specified at 29/32", same as the nitrophyl and the measurement point is the end of the float, not the higher point t towards the middle as shown in the following image:

The early/original brass float is measured at the point similar to the nitrophyl, but is usually specified at 1" or 1-1/16" in some cases.

 

[Challenger RTA]

Thanks for the above measurement. There was some gasket interference but that aways gets trimmed off. I wanted to use the new brass floats. But the arm is flipped. If I remember it was about an inch higher then the setting. It would take more that a tweaking to adjust. Maybe I'm just looking at wrong. I think I took a picture of it. I'll check it again. I did ask the seller about it and they said it will work. So I ask show me an example of it installed. They said they have to contact the suppler. Never got it!

 

[Challenger RTA]

Spinning my wheels today on something else. So I pulled the TQ this afternoon. Took it apart check all passages with mig wire. Checked needle and seat, clean. The bowl had a light brown film in the bottom. Cleaned right up. Primary well seals look to have a film replaced them anyhow. Throttle plates where closed and light could be seen in arears around them.
A thanks to a pro for the measurement that worked for the brass floats.

 

[Ricks72Chlgr440]

To me, the thermoquads are a thing of beauty. I'd run one today if I could get the strip kit like I was able to back in the 80's!

 

[Challenger RTA]

To me, the thermoquads are a thing of beauty. I'd run one today if I could get the strip kit like I was able to back in the 80's!

I agree! Simplicity at it's best! They were rocket scientist with pencil paper and a slide rule. Only the bean counter cheapen their work!

 

[Vaanth]

View attachment 137232

Although it sounds like you may already have the float setting sorted out, following is a better image of the float specification of the aftermarket brass float from a manufacturer, and some better images comparing floats, plus images of a mock measurement of the aftermarket float height setting.

 

[Challenger RTA]

The above takes away the second guessing or doubt of what I did. Thanks for you info. Looking to put it on shortly. But things in life get in the way. Now I'm questing the fuel it's self. Years back Everything was new. Fuel pump, fuel lines copper nickel, fuel tank, fuel filter and all new ethanol parts in the carburetor. I knew it was rich but keep it cleaned up by tune up. Then it ran rough starting this year after sitting over winter. There again a tune up made it better but not like it was or should be. Once again Thanks.

 

[Challenger RTA]

Just got done taking the s#0w plow off. Wander what's going to happen?

 

[mrmopar340]

Just got done taking the s#0w plow off. Wander what's going to happen?

Burnouts!