Thermoquad running rich

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dartfreak75

dartfreak75

Restore it, Dont part it!
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I pulled the plugs yesterday on my freshly rebuild 360 with freshly rebuild thermoquad, and with my limited plug reading skills I have determined its running extremely rich. Which I kinda already knew because the exhaust is very rich smelling. But the plugs are very black and sooty.and smell very strong of gasoline I didn't take any pictures but I can if yall want to see them. My question is where should I start at leaning it up some? Should I start with the mixture screws or the metering rod or Jets?
 
to be honest, as much as you've had spark issues, i wonder if your spark is very weak. I have to question that as well as the carb, or before the carb I should say.
 
318willrun said:
to be honest, as much as you've had spark issues, i wonder if your spark is very weak. I have to question that as well as the carb, or before the carb I should say.
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That is a very good point ! I didn't even think of that! I have a points dissy now I could try and see if anything changes! I don't have a air to fuel guage so all my testing will be done my senses.
 
dartfreak75 said:
Should I start with the mixture screws or the metering rod or Jets?
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As said check spark and you can adjust your Idle circuit but the rest sounds like your talking about Eddy carbs. No metering rods in a Thermoquad and they take some doing with jetting. JMO but haven't ran a TQ in years. They are a good carb. though. Maybe someone with more TQ experience can chime in. A bad or non seated float valve can cause some rich issues as well.
 
Kendog 170 said:
As said check spark and you can adjust your Idle circuit but the rest sounds like your talking about Eddy carbs. No metering rods in a Thermoquad and they take some doing with jetting. JMO but haven't ran a TQ in years. They are a good carb. though. Maybe someone with more TQ experience can chime in. A bad or non seated float valve can cause some rich issues as well.
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Isn't the bar that goes up and down in the center considered a metering rod on a tq? It was professionally rebuilt by our very own @Dana i don't think it's a float valve issue. It may be spark related tho.
 
dartfreak75 said:
I pulled the plugs yesterday on my freshly rebuild 360 with freshly rebuild thermoquad, and with my limited plug reading skills I have determined its running extremely rich. Which I kinda already knew because the exhaust is very rich smelling. But the plugs are very black and sooty.and smell very strong of gasoline I didn't take any pictures but I can if yall want to see them. My question is where should I start at leaning it up some? Should I start with the mixture screws or the metering rod or Jets?
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How much have you driven the car?
 
dartfreak75 said:
Not much. Maybe 2 miles but not all at once lol
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Well maybe 5 miles to the end of my road is a 1/2 a mile iv done that and back twice so that would be 2 and I took it to my neighbors and back about 6 times ans that a quarter mile each way so another 3
 
dartfreak75 said:
Not much. Maybe 2 miles but not all at once lol
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Then you cannot read plugs and expect them to read right. Think about what you're reading. 99% sittin in the yard idling and revving. They're reading corrrectly for THAT. You're puttin the cart before the horse.
 
RustyRatRod said:
Then you cannot read plugs and expect them to read right. Think about what you're reading. 99% sittin in the yard idling and revving. They're reading corrrectly for THAT. You're puttin the cart before the horse.
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Oh ok I didn't know that mattered! Thanks buddy!
 
dartfreak75 said:
Oh ok I didn't know that mattered! Thanks buddy!
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Yeah. I've tried to explain how to do this before, but got accused of talking down to members, so I just shut up. But you cannot read plugs like you are trying to do. It might be rich, but the "read" you're looking at is as far from accurate as you can get.
 
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Take it for a good long drive to burn some crap off. Some people will find a stretch of road and wind it up full throttle then shut it down pull over a look at a plug. But I use a A/F gauge so I can see all three stages of mixture. Idle/cruise/ and Wide open throttle.
 
Yes there are metering rods , thermoquads were designed for emission style motors and if running properly are not going to run rich. I would be looking at float level, how is your timing. Also let the motor set after running and see if you have dripping fuel or a leak into the manifold that would indicate a problem.
 
dartfreak75 said:
I pulled the plugs yesterday on my freshly rebuild 360 with freshly rebuild thermoquad, and with my limited plug reading skills I have determined its running extremely rich. Which I kinda already knew because the exhaust is very rich smelling. But the plugs are very black and sooty.and smell very strong of gasoline I didn't take any pictures but I can if yall want to see them. My question is where should I start at leaning it up some? Should I start with the mixture screws or the metering rod or Jets?
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I ran thermoquads for years, and they were excellent carburetors. Back when we could by strip kits, I would tune the carb to perfectly compliment the 440 in my Charger. Since your engine is new, do what the others have said and put some miles on that dude. Before taking it on a drive, do what K.O. said and run the engine & then let it sit and look for any spillage into the throats of the carb. If none, then go for a drive. Does it start ok, or do you have to crank it a long time? Does the choke fully come off when the engine is warm? Do you have to keep it revved up while it is cold to keep it running? When properly set, you should be able to pump it once and hold the throttle about 1/2 way down and it should fire right up and keep running.
 
dartfreak75 said:
Isn't the bar that goes up and down in the center considered a metering rod on a tq?
...... i don't think it's a float valve issue. It may be spark related tho.
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The bar that goes up and down is called the metering rod tree. The rods hang on the ends.

You can bend a AFB rod 3/4 or an inch shorter and clip the ends off. The rods are thicker than TQ rods. This is a problem to use on the smaller holes on the metering rod tree. Adapt and overcome!!!!!

If the bottom well cap under the jets ever come off & you have the good luck that it didn’t break, you can re-tap the TQ jet threads for Holley’s jets. (FWIW)
The Holley jets will need minor mods.

Address your weak spark. Up the coil power output. FWIW, a multiple spark box is very good for the low cruise rpm’s. & to help with a cleaner idle.

As mentioned earlier, the TQ was born a race carb, not an emissions carb. This is fact. They made there appearance in ‘69. 2 years before they were stock components.
 
rumblefish360 said:
The bar that goes up and down is called the metering rod tree. The rods hang on the ends.

You can bend a AFB rod 3/4 or an inch shorter and clip the ends off. The rods are thicker than TQ rods. This is a problem to use on the smaller holes on the metering rod tree. Adapt and overcome!!!!!

If the bottom well cap under the jets ever come off & you have the good luck that it didn’t break, you can re-tap the TQ jet threads for Holley’s jets. (FWIW)
The Holley jets will need minor mods.

Address your weak spark. Up the coil power output. FWIW, a multiple spark box is very good for the low cruise rpm’s. & to help with a cleaner idle.

As mentioned earlier, the TQ was born a race carb, not an emissions carb. This is fact. They made there appearance in ‘69. 2 years before they were stock components.
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I recall around '79 that Carter came out with the 9801 (I believe it was), which was an aftermarket replacement. I loved that because it came with an electric choke. Ah, the days!
 
Kendog 170 said:
As said check spark and you can adjust your Idle circuit but the rest sounds like your talking about Eddy carbs. No metering rods in a Thermoquad and they take some doing with jetting. JMO but haven't ran a TQ in years. They are a good carb. though. Maybe someone with more TQ experience can chime in. A bad or non seated float valve can cause some rich issues as well.
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I stand corrected. Good info.
 
Ricks70Duster340 said:
I recall around '79 that Carter came out with the 9801 (I believe it was), which was an aftermarket replacement. I loved that because it came with an electric choke. Ah, the days!
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Yes, a Chrysler throttle arm and a Chevy throttle arm.
800 cfm rated, small primaries, & the electric choke that work’s great! Carter called it there “ Rochester replacement carb.”

I don’t know what the deal was with the QJ back then? Must have been something.
 
I would take the plugs out and sandblast them, and reinstall.
 
Ricks70Duster340 said:
I ran thermoquads for years, and they were excellent carburetors. Back when we could by strip kits, I would tune the carb to perfectly compliment the 440 in my Charger. Since your engine is new, do what the others have said and put some miles on that dude. Before taking it on a drive, do what K.O. said and run the engine & then let it sit and look for any spillage into the throats of the carb. If none, then go for a drive. Does it start ok, or do you have to crank it a long time? Does the choke fully come off when the engine is warm? Do you have to keep it revved up while it is cold to keep it running? When properly set, you should be able to pump it once and hold the throttle about 1/2 way down and it should fire right up and keep running.
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It starts good even when cold. If it hasn't been ran in a couple days I have to pump the gas a few times. The choke works good its fully opens and when warm and closes when cold. It will fire right off and idle i don't have to feather the gas or anything to keep it running. I can get in it and pump the gas a couple times turn the key and it fires up. And I can walk away and it will purr like a kitten lol.
 
Fact , you... Paragraph 2 thermaoquad was designed as a emission capable carburetor.and even if it did come from a testing racing background , the ones that found their way on production engines were of a emission consideration design. They are a awesome performance carburetor there's no doubt ! but it is what it is.

Screenshot_20210427-195152.png
 
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I love the TQ.
IMO, she is the most versatile factory street carb ever designed.
Ok lemmee qualify that;
IMO, the most versatile carb I have ever owned or worked on. Just two carb-sizes covers the entire engine line up from the 318 to the 440.
To do what just one TQ can do, I think you would need a fleet of PV-equipped Holleys.
 
AJ/FormS said:
I love the TQ.
IMO, she is the most versatile factory street carb ever designed.
Ok lemmee qualify that;
IMO, the most versatile carb I have ever owned or worked on. Just two carb-sizes covers the entire engine line up from the 318 to the 440.
To do what just one TQ can do, I think you would need a fleet of PV-equipped Holleys.
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Three sizes. 800, 850 and 1000.
 
K.O. SWINGER said:
Fact , you... Paragraph 2 thermaoquad was designed as a emission capable carburetor.and even if it did come from a testing racing background , the ones that found their way on production engines were of a emission consideration design. They are a awesome performance carburetor there's no doubt ! but it is what it is.

View attachment 1715729732
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The first Thermoquads produced were the Competition Series 850 and 1000 in 1969 and were in no way, shape, form or fashion connected to anything resembling emissions. They were a race bred carburetor designed around and for racing. That's what the fact was, is and always has been.
 
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