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Babyblue66

Babyblue66

Cool dude
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In an apartment, MN
I have a 72 340 Thermoquad. It works great in normal driving and under full throttle, but after you open the secondaries and go down to idle it runs rough and rich for a while untill you rev it a few times then back to normal. The secondary shaft has play and I believe the butterflies hang up and is causing these problems. I've had this carb for years and had to unhook the secondaries when I ran it for a while on a 360. It runs good and has nice power on my lightly hopped up 273 but that damn issue is puzzling. All I can come up with is the worn shaft. Can you repair this or do I need a different bottom plate?

I just went through the carb again today. Cleaned, checked float levels, gaskets etc. All looks well.

I have a couple bigger TQuads that have always been excellent carbs on 440's and 360's. I would really like to use this smaller one if I can fix it, or get it fixed.
 
get rid of that thermocrap and you will be better off. my freinds and I have never had a thermocrap ever work properally.
 
Well thanks for helpin with answering the question, you the man.

I guess you never learned what it takes to tune a carb, but that's ok, people trash things for this reason.

Weird, all my T-Q's worked fine. Hummmmmmmmmm
 
rumblefish360 said:
Well thanks for helpin with answering the question, you the man.

I guess you never learned what it takes to tune a carb, but that's ok, people trash things for this reason.

Weird, all my T-Q's worked fine. Hummmmmmmmmm
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Mine too, except this weird problem. Thermocrap huh? My 273 has more power with this carb than a 600 vac holley, thats on it now. And my mileage sucks with the Holley. I have nothing against any carbs, I prefer Holleys for more radical engines and I have 2 600 Edelbrocks on my built 440. And Thermoquads make excellent everyday carbs on mild engines. So unless you have a logical reason you can carefully explain to me, the retarded Thermocrap comments are just that, retarded.
 
Hang10Dustin said:
get rid of that thermocrap and you will be better off. my freinds and I have never had a thermocrap ever work properally.
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It might be time to hit the edit button Hang10. The natives seem to be restless tonight. ;)

BTW: I am also a big fan of TQs. When they are running correctly & tuned properly (like any other carb), they are efficient/powerful carbs. Of course, the efficient/powerful part depends on how you drive it. ;)
 
Hang10Dustin said:
get rid of that thermocrap and you will be better off. my freinds and I have never had a thermocrap ever work properally.
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A statement of ingnorance for sure.All my thermoquads have performed better than the holleys and eddies I have had ,given better power and mileage in addition to being dirt cheap and easier to fix. My 4 year old can work on them. In fact I like thermoquads so much that if you have any I'll take that "thermocrap" off your hands free of charge.
 
I have never seen any T.Q.'s with worn 2ndary shaft bore; has the green Teflon coating been removed from the shaft? Repair depends on which end of the 2ndary shaft has the wear ie the driver or the passenger side. The problem with the wear on the passenger side is that the shaft does not go all the way through the casting on the passenger side. That is not to say that the repair can not be made though. Also are your sure the problem might be that the butterflies are not closing completely every time? Carbon build-up on the front/rear edges will cause this, David.
 
Hang10Dustin said:
get rid of that thermocrap and you will be better off. my freinds and I have never had a thermocrap ever work properally.
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It isn't rocket science figuring out a T.Q.; plenty of people have and they absolutely are a fantastic carb, both in performance and gas mileage.

I do not use Holley carbs but I will not argue against the use of one. Besides, I have had my share of poor performing Holleys, Edelbrocks, Ball & Ball ect. If the carb isn't right, make it right with a repair or re-build.
 
If I've learned one thing over the years it's that a carburator is brainless therefore it depends on the brains of it's owner to make it operate correctly.:toothy10:

Terry
 
demon sizzler said:
If the carb isn't right, make it right with a repair or re-build.
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No doubt. I'm not a TQ guy but I know Holley's by heart so that's what I prefer to use. That's not to say that a TQ is a bad choice, I just use Holley's because I know them, not because they are necessarily a better carb.

demon seed said:
If I've learned one over the years it's that a carburator is brainless therefore it depends on the brains of it's owner to make it operate correctly.:toothy10:

Terry
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'Zactly!
 
ramcharger said:
No doubt. I'm not a TQ guy but I know Holley's by heart so that's what I prefer to use. That's not to say that a TQ is a bad choice, I just use Holley's because I know them, not because they are necessarily a better carb.
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Like I allways write, what ever your comfy and messing with, use it.

I'll use any carb without any concern, it just takes time and effort to learn anything and new things are a pain until you get it.
 
demon sizzler said:
I have never seen any T.Q.'s with worn 2ndary shaft bore; has the green Teflon coating been removed from the shaft? Repair depends on which end of the 2ndary shaft has the wear ie the driver or the passenger side. The problem with the wear on the passenger side is that the shaft does not go all the way through the casting on the passenger side. That is not to say that the repair can not be made though. Also are your sure the problem might be that the butterflies are not closing completely every time? Carbon build-up on the front/rear edges will cause this, David.
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It is very clean, I went throught it a couple days ago. As I stated I have had other TQuads on other cars and have been great carbs when tuned. I know carbs fairly well, and have rebuilt and tuned many carbs from Holleys to Edelbrock dual quads on my Coronet, to 4 Kehins on my Honda.This one is being just strange. It does have more movement in the secondaries than my other carbs, thats the only thing I can find wrong. Do you possibly have a different base plate to sell? I have no 800cfm ones to try.
 
You may also want to check for wear on the link bar and slide that connects the secondaries to the primaries. Any binding there may hang them open. Try to make it do it in park and have a friend use a screwdriver to reach down and tap the secondary plates closed... If there is movement, find where it's binding. The Thermoquads IMO are a killer carb. But with parts hard to find for the typical hobbyist, and the voo doo that's been spun about them, some people just find replacing them easier. I'm still looking for a couple new Competition Quads for my "stock".
 
I think the link between the primary and secondary was out of adjustment. I checked it with my other carbs. I bent the rod a little but I haven't tried it yet.
 
Babyblue66:
JMO, but the Thermo-Quad isn't any better or worse than any other carb. It's just a little temper mental at times. I hope you can get yours to work. Seems like everyone will have an opinion about the Thermo-Quad, but not many have real experience using or tuning one. The competition series TQ was more than adequate for drag racing back in the day. The smaller Themo-Quad is a good street carb when set up properly for sure.
 
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