Struggling with my Thermoquad

[340SHAKER]

Hey guys, if anyone can help out I would appreciate it very much. I'm struggling with a Thermoquad. I have a 1971 on a 340. I have had several of these in the past and never had any problems with them. I sent this one off and had it restored about 5 years ago. I ran it on the engine test stand about 3 years ago and it seemed to run great. Now after completing the car it is running super rich. So much that it is smoking black most of the time. I tried adjusting the idle mixture screws but it doesn't change anything by turning them in or out. I have turned them all the way in and engine still runs. My experience in the past was that the engine would stall when they where turned in too far. I noticed that when the engine is idling with the choke fully open there is a slow drip of fuel coming out of the tubes located in the round part (venturi I think). It's the tube in the picture with the yellow line pointing to it. I don't think this is supposed to be happening. Can anyone tell me if this is normal? What is causing it? How do I correct this? I really want to drive this thing but it's embarrassing the way it is running. Thanks so much for any guidance.

 

[Chryco Psycho]

You need to remove the top & check the float level , there is also a round seal at the bottom of the wells if it is out of place will dump fuel like crazy internally . There could be dirt in the needle & seats also .

 

[340SHAKER]

I was wondering about the floats. Do you think they are stuck or just set incorrectly?

 

[Chryco Psycho]

set incorrectly or dirty .

 

[340SHAKER]

I will take it off this weekend to see what I find. Thank you.

 

[Chryco Psycho]

I will be checking in if you need help .

 

[704406]

You said you ran it 2-3 years ago, did you dump out the fuel and leave the carb dry or leave the fuel in it all this time and it's gone bad. If you left fuel in it the seals in the well that Chryco Psycho mentioned could be rotted from bad fuel. The floats and needle and seats could be stuck and sticky with bad fuel as well.

 

[340SHAKER]

Thanks guys, I did store it dry. Question, are both floats supposed to be the same? These two look identical. with the exception of having different numbers molded in them. One has an A 23 and the other has an A 40 molded in it. I'm wondering because one corner of the float has like a 45 degree chamfer on it. When there installed this chamfer is on the outside of one float and the inside of the float on the opposite side. I would have thought they should be a mirror image rather than a copied image. I did check the float setting and both were 1 1/16". However when I would lift and drop the float to check and remeasure one side would bounce off the needle a bit and one side would not bounce off the needle. I noticed that the little tab on the float that contacts the needle was bent more on one float than the other and that float would contact the carb housing before hitting the needle. I bent the tab to match the opposite side and now both "bounce" off the needle so that side may not have been sealing. Another thing is that I have read and heard that the two O-rings need to be in good shape. This is a one year only carb, 1971. I don't see these two O-rings in mine. Picture attached. Am I blind, or is the 71 different?

 

[Chryco Psycho]

The float setting should be done with the top of the carb upsidedown , measure between the float & the top of the carb both should be equal height , sounds likeyou found the problem if the float would hit the body before stopping on the needle though . I don't have the correct float spec handy sorry .
The floats being slightly different is ok .
I have not seen any Thermoquad that did not have the O rings in the wells , you may have to buy a rebuild kit to get them .

 

[340SHAKER]

OK, thanks. Where would these O-rings go? I don't see a place for them, can you see on the pictures I attached where they should be?

 

[Chryco Psycho]

My good computer died a month ago so I lost all of my pictures & tools , it seems I cannot edit the picture on this computer I am borrowing , or I don't know how but they usually sit at the bottom of the tube that reaches the floor of the bowl beside the jet .

 

[340SHAKER]

I thought on the videos I've seen there was a round cup on the base of the bowl that the o-ring goes into. I don't see these cups in my bowl. Wondering if '71 was different???

 

[340SHAKER]

I just checked out the video again and my bowl is for sure different than that one. I'm guessing no O-rings.

 

[Adam]

Sometimes the plastic main body will develop cracks at the bottom of the float wells. They separate a little and leak internally. Look at the bottoms of the main body very carefully. I have had this happen to two TQs. I would remove the base plate and inspect the bottom of the main body as well. If you find separation you will need a new main body, IMO. I tried JB Weld and other epoxies that were supposed to be resistant to gas, but they all failed eventually.

 

[340SHAKER]

I will inspect it. Thank you.

 

[/sixchall]

340 Shaker.......I have a pair of NOS Thermoquad floats like the ones you’ve pictured. I’ve had them for a long time in the Mopar box I can’t use them but if your interested we can kick this around and make it happen. For the Thermoquad 1971-1985. Give me a shout out. Thanks, Al

 

[340SHAKER]

Al, thank you. I will see how this works out. I have the carb ready to bolt back on. I will hopefully have it running in the morning. I need to get some work done the rest of today. Have a great weekend everyone.

 

[/sixchall]

340 Shaker.....ok buddy, see how that carb performs for you, hope it works out for you. If you need these floats they are available for you and are a matched set. Give me a holler. Thanks for the quick response. Al

 

[Chryco Psycho]

Could be a different design without the O rings , if so they should have continued to use that design !!
71 was the first year Mopar used the TQ

 

[/sixchall]

If you decide you need them here’s a pic, thanks, Al