Base Plate question Thermoquad

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    Author Topic: Base Plate question Thermoquad  (Read 3018 times)

    Offline brasil

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    Base Plate question Thermoquad
    « on: April 28, 2015 - 02:25:16 PM »
    Hello Guys....

    I will rebuild my "new" 6139S TQ next weekend...  I disassambled the carb yesterday...and found something strange. The carb has a kind of VALVE in the baseplate... between the secondarys...the "valve " leeds into the manifold... 
    Now the question...  In the rebuild kit are different base gaskets....  does someone here have a foto from the right gasket ??

    Thank you Juergen


    Update :
    made a little search in the www    this Valve should be the   HOT IDLE VALVE  ....  interesting -because I have 5 TQ Carbs....but only the 6139S has this valve....  didn´t Carter use this valve only in the "Older " Carbs ?
    « Last Edit: April 28, 2015 - 04:53:10 PM by brasil »
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    Offline cudabob496

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    Re: Base Plate question Thermoquad
    « Reply #1 on: April 28, 2015 - 04:54:11 PM »
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    72 Cuda, owned 25 years. 496, with ported Stage VI heads, .625 in solid roller, 254/258 at .050, 3500 stall, 3.91 rear. 850 Holley DP, Reverse manual valve body.

    1999 Trans Am, LS1, heads, cam, headers, stall, etc! Love to surprise the rice rockets with this one. They seem so confident, then it's "what the heck just happened?"

    2011 Kawasaki Z1000

    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #2 on: April 29, 2015 - 04:53:26 AM »
    Thank you for the  link..

    but unfortunatly the videos don´t answeer my question. The carb I have has this  HOT IDE VALVE situated between the secondary trottle blades ...  and
    also brass floats...

    Perhaps another idea how to deal with this "valve "? ..  the other carbs I have  don´thave this valve...  that´s why I am concerned


    Greetings
    Juergen
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    Offline Bullitt-

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    Re: Base Plate question Thermoquad
    « Reply #3 on: April 29, 2015 - 05:51:54 AM »
    I have rebuilt one Thermoquad that had this "Hot Idle Compensator" valve. I wish I could remember more I only know that it was not an issue, i just followed whatever instructions I had at the time

    Pages 10-13 may help you  http://www.walkerproducts.com/wp-content/catalogs/carburetor/by-model/carter.pdf
    Cork gasket on valve & of course selecting the appropriate base gasket

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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
    Screwed by Photobucket!

    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #4 on: April 29, 2015 - 10:07:28 AM »
    Hello   Bullitt,

    no, not the  Hot Idle Compensator....   My carb has a  "Hot Idle Valve "  this valve is located in side the base plate of the carb... 

    I will make a foto or two...to show you what I am meaning

    Greetings Juergen
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    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #5 on: May 02, 2015 - 01:01:29 PM »
    Here are some pics of my base plate.... also you can see this " VALVE "...that is located in the base plate

    Greetings Juergen
    « Last Edit: May 02, 2015 - 01:55:21 PM by brasil »
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    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #6 on: May 03, 2015 - 11:39:47 AM »
    Nobody ever had a TQ with this "Valve "....??

    i searched all over in the www the last days... but this "hot idle Valve " is unknown..   ( but as you all can see...exists

    Greetings Juergen
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    Offline Bullitt-

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    Re: Base Plate question Thermoquad
    « Reply #7 on: May 03, 2015 - 05:40:09 PM »
    Like I stated previously I have rebuilt one Thermoquad that had this "Hot Idle Compensator" valve. I wish I could remember more I only know that it was not an issue. I replaced the cork gasket & reinstalled.

    I don't have the carburetor in front of me to disassemble. The only question I see is which gasket to use to which all I can say is to match the old gasket to a new one as there are subtle differences.

    The only thing I can glean from the internet is that the Hot Idle Compensator valve opens to lean the mixture out & that it was only used in certain earlier production models which seems to be correct for your car. 

    Do you have other questions?

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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
    Screwed by Photobucket!

    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #8 on: May 04, 2015 - 08:43:10 AM »
    Hello bullit,

    thank you for your help.   I looked at the gaskets...and they all have  a hole in same position... so the gasket should be o.k.  The base plate says  6139 S
    so it is a 1972 base plate..  It is intresting that they  leaned out the mixture...because this 1972 carb is a  pre SMOG carb...

    Hope that this  "valve " doesn´t make any trouble...  i.e  leaning out the mixture over the full "working area " of the carb..   
    I used 098 primaries  1966 rods  and 0137 secondaries  in my built.  The 1973 carbs used this Set up.....  in 1972 the primaries were 095   with 1940 rods
    ( way leaner...don´t know why ? )

    But my engine is /was built to the 1970 spec.  with 10.5 CR  Purple cam  big valve heads...and 1971 intake  with HP Manifolds also...
    So I decided to go with the  "richer " jetting...  to feed the  "beast"

    Next days I will go for a test drive, and will let you know how it worked

    Greetings Juergen
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    Offline Bullitt-

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    Re: Base Plate question Thermoquad
    « Reply #9 on: May 04, 2015 - 09:31:19 AM »
    It sounds like you understand the Thermoquad well.  One thing I learned from a local Mopar owner using a Thermoquad on his modified engine that lacked the vacuum of a a stock engine is that a lighter Step Rod Piston Spring was necessary for his to operate properly.

    Good Luck
    Wade
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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
    Screwed by Photobucket!

    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #10 on: May 04, 2015 - 12:13:15 PM »
    Hello Wade....

    yes the Step up spring....  this would be the " holy grail"....  my vacuum is around 12-14 inches of Mercury...  so I hope that the spring I have right now
    will do their job. Unfortunatly  Carter never made different step up springs for the TQ   only for the AVS /AFB carbs...and these springs are way different...

    Greetings Juergen
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    Offline brasil

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    Re: Base Plate question Thermoquad
    « Reply #11 on: May 10, 2015 - 04:11:45 PM »
     :ylsuper:

    one more TQ alive !  Made 200 + miles with the 6139S TQ  this weekend   ...the Chally runs like a dream now.. AFR while cruising 14.6-15.0    light trottle 13.5- 14.0   WOT  11.8 

    I used  98 jets ( the "book"says  95 jets...but they are way to small ! ) and 1966 rods   on the primary side   and 5137 Jets on the secondaries...  The air valve has @ 0.04 ( 1mm)  slack.. and the spring tension is dialed in ...at 1 1/4 turn from just contacting the topbase...   
    I still need to lean out the secondaries just a  tad...so I will allow the air valve to open just a bit more...  to lean out the mixture..

    close to fuel injection....   8)


    Greetings Jurgen

    P.S  with TF 727   and  3.23 rear  the Chally makes now 16 mpg !  Mix of city and country roads  ( lot of hills also )  I think that is pretty good....

    Now I will start rebuilding  the next TQ that I have still on the shelf.

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    Offline Bullitt-

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    Re: Base Plate question Thermoquad
    « Reply #12 on: May 11, 2015 - 07:54:10 AM »
                         :woo:    :cheers:
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    Wade  73 Rallye 340..'77 Millennium Falcon...13 R/T Classic   Huntsville, AL
    Screwed by Photobucket!
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