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edumacate me on thermoquads

Discussion in 'The Hokey Ass Message Board' started by your wheelbase is how big, Aug 3, 2009.

  1. i have a slightly o/t jensen inteceptor in the garage for repairs and it runs like a sack of shit its over fueling like a bastard and its been sitting for about 15 months so im thinking float levels etc but i never dealt with these carbs except walking past them at swap meets to get the holleys any advice would be most welcome.
  2. Rust Monkey
    Joined: Apr 9, 2009
    Posts: 75

    Rust Monkey

    As far as the operation, just think Carter AFB with plastic fuel bowls and HUGE secondaries. My only word of advise is be careful no to crack the center section either when taking them appart for by overtightening during reassembl, and use a straight edge to verify good flat mating surfaces as the plastic bodies have been known to warp (and can cause flooding like you describe). Not bad carbs though.
  3. thanks for the reply the thing is i dont know anything about afb type carters either i only know holleys maybe i should just convert it to a 750 or something its a 440 jenson so witch size of carb would suit best.
  4. carbking
    Joined: Dec 20, 2008
    Posts: 2,913


    (Opinion) - the TQ is the finest STREET 4-barrel ever built anywhere at any price.

    They have two major issues:

    (1) Carter used "X-rings" for a seal, most aftermarket kits use "O-rings" (approximately 1/1000 the cost of an X-ring). As one might guess, the O-rings do not work as well.

    (2) The infamous "warped" plastic bowl. The damage occurs when a novice tries to take the carburetor apart, and removes the 8 screws which hold it together. After shaking, tapping with a plastic hammer, tapping with the handle of a screwdriver, etc., the novice gets impatient, and starts prying with a screwdriver and CRACKS the bowl. Then when he/she shows it to someone more experienced, he/she is shown the 2 HIDDEN screws beneath the choke butterfly. When asked about the carburetor, the novice then states the carburetor had a WARPED bowl.

    The carb flows approximately equivilent to a 935 CFM Holley.

    I would suggest rebuilding it.

    With 150,000 carbs to choose from in stock, I chose a TQ for my own very high performance street car.

    rat bastad likes this.

  5. 4-pot
    Joined: Aug 12, 2005
    Posts: 181


    I agree with carbking excellent carbs, I have used a lot of them.I prefer them to holleys. If it ran ok before sitting a simple rebuild should do the trick. If the problem was there before you will have to do a little more detective work. good luck.
  6. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,353

    el Scotto
    from Tracy, CA

    I like Thermoquads, even though I have Holleys on everything right now. I ran a Thermoquad on one of my first 440s I built, you definately knew when those secondaries opened up!

    The last 440 I bought had really nice Thermoquad on it, I should rebuild it for the 440 in my Challenger.
  7. Nothing wrong with the TQ tyeyre a great carb, but like anything else, you have to know how to dial one in.

    And that's where shadetree mechanic's get caught out.

  8. 50dodge4x4
    Joined: Aug 7, 2004
    Posts: 3,535


    I have a love-hate relationship with the Thermoquads. When they work, I love them, when they don't work, I hate them. Seems as a good rebuild is good for a year before something messes up, then it takes a huge effort to get them back to working again. I've got 5 or 6 of those things.

    I finally got fed up with the one on my 4x4 and put on an AVS (an old Carter off of a Mopar, not the eddy version) with and adaptor plate. I'll see how that one works out. Gene
  9. twofosho
    Joined: Nov 10, 2005
    Posts: 1,153


    The same could be said of a Quadrajet. When they work, they work, and when they don't, good luck. In fact I used to say it all the time when I street raced a 68 Camaro with "one of the good ones" on it almost 30 years ago now.

    Never will forget the kid one that swore up and down one night the car couldn't possibly be fast because of the Q-jet and stock orange rocker covers. Funny, he wouldn't put his money on the hood against it, and he certainly wouldn't race it.

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