Thermoquad problem

Posted By: LemonTwiist

Thermoquad problem - 06/26/08 01:21 AM

I rebuilt a 4973S 71 Auto Thermoquad for a 340 recently and find that it will not keep running when I start the engine. The only way to keep the engine running is to pump the pedal and all I see is the accelerator pump squirters putting fuel into the intake. any ideas on adjustments or am I missing something?

Posted By: r69cuda

Re: Thermoquad problem - 06/26/08 02:17 AM

Did you remeber to put the 2 rubber O rings in?

Posted By: 440trk

Re: Thermoquad problem - 06/26/08 02:38 AM

71 TQ's are unique. I would try to get in touch with Member "Demon Sizzler" here on the board...I believe he is the most familiar with them by far.

If nothing else, It looks like you're only 20 min or so from me...I may be able to swing by and give you a hand with it, if you think it would help.

Let me know.

Posted By: LemonTwiist

Re: Thermoquad problem - 06/26/08 10:13 AM

The zip kit that I got did not come with any rubber o-rings. There are two metal flat washers that I don't know where they go. Would they use washers for the jets? I think I read somewhere that the jets for 71 screwed in. Not pressed in?

Posted By: LemonTwiist

Re: Thermoquad problem - 06/26/08 10:22 AM

Thanks I PM'd you

Posted By: 440trk

Re: Thermoquad problem - 06/27/08 04:48 AM

Quote:

Thanks I PM'd you

Sent ya an e-mail back.

Posted By: LemonTwiist

Re: Thermoquad problem - 06/28/08 03:19 AM

OK here's the latest. If I put a rag in the front primary ports the engine runs fine. When I remove the rag the engine dies. Is that a vacuum leak? or is it a problem of too much air being ingested into the carb? Whats the fix?

Posted By: LemonTwiist

Re: Thermoquad problem - 06/29/08 11:53 AM

ANYONE Have any ideas?

Posted By: mark7171

Re: Thermoquad problem - 06/29/08 02:47 PM

it soounds like your choking it for cold starts with a rag.

by chance its close enough to meet the resistance it needs to pull the venturi.

Posted By: LemonTwiist

Re: Thermoquad problem - 06/29/08 03:54 PM

I would agree, but there is not mention in any of the sources I have found that tells me how to adjust the idle set screws or the idle circuit. There seems to be not enough vacuum at idle to pull the fuel through the venturi

Posted By: HotRodDave

Re: Thermoquad problem - 06/30/08 02:24 AM

Usually the mix screws end up about 2.5 turns out.

To set basic idle speed for a firs start up after rebuild I flip the carb over and open the speed screw as much as I can with out uncovering much of the transfer slot, mabey .050 of it.

This will almost always get them idleing where you can adjust them.

Posted By: LemonTwiist

Re: Thermoquad problem - 06/30/08 10:46 AM

"To set basic idle speed for a firs start up after rebuild I flip the carb over and open the speed screw as much as I can with out uncovering much of the transfer slot, mabey .050 of it.

This will almost always get them idleing where you can adjust them"

OK you lost me. I'm not sure what you are referring to. I have a 71 carb and I don't recall seeing any screw that would affect the transfer slot?

Posted By: boydsdodge

Re: Thermoquad problem - 06/30/08 12:46 PM

Here is a link to Demon's site, I think that you might have the primaries misadjusted.
How are the shafts?
New base gasket?(use the thick one, not the thin one that most kits come with.)
If you can't figure it out get someone that can.
These are great carbs for a street driven car.
Do a bunch of reading before you start tearing away at it.

http://www.thermoquads.com/page204.html