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Carter Themoquad adjustment

Posted By: LL340Rag

Carter Themoquad adjustment - 03/21/10 04:09 PM

I have a Carter Thermoquad 4 barrel on a decently built 340. The thing runs so rich the flies drop dead around it. It has just been rebuilt but not setup yet. Other than the 2 basic screws how do you lean this thing out?
Posted By: DynoDave

Re: Carter Themoquad adjustment - 03/21/10 05:11 PM

You might want to thumb through this. The adjustments need to be done in a specific order.

Imperial Club

Any idea on jets and rods? Are they stock? Is that an original 340 or small block carb?

Do you know if the carb. rebuilder replaced the o-rings in the bowl area? They can leak and lead to a rich condition (see p.11).
Posted By: LL340Rag

Re: Carter Themoquad adjustment - 03/21/10 05:55 PM

Jets and rods are stock. It is a 72 340 carb 6133S I believe. Correct for a 340. Everything was replace in the rebuild. I believe I just need to adjust the metering rods, just not sure how and the manual is little help.
Posted By: 70AARcuda

Re: Carter Themoquad adjustment - 03/21/10 06:15 PM

http://www.thermoquads.com/page204.html
Posted By: LL340Rag

Re: Carter Themoquad adjustment - 03/21/10 06:30 PM

Thanks. More work.
Posted By: ademon

Re: Carter Themoquad adjustment - 03/21/10 06:32 PM

did they reseal the jet wells?
Posted By: dOc !

Re: Carter Themoquad adjustment - 03/21/10 07:30 PM

Who rebuilt it ? .. I ask this because some people mix-up big-time the primary rods and jets. Is this rich through ALL the cycles? ,...what floats are in it?
Posted By: Rug_Trucker

Re: Carter Themoquad adjustment - 03/21/10 07:35 PM

I'll second checking the resealing of the jetwells. Also check the float height. I has to be checked with the gasket in place. Measure from the gasket surface.
Posted By: dOc !

Re: Carter Themoquad adjustment - 03/21/10 07:58 PM

What is all this JET WELL chat ? ... is this what you guys have seen lots ? ... I have rebuilt more than my share of TQ's .. but I have only seen that prob once.

Which year/model carbs are prone to this issue ?
Posted By: LL340Rag

Re: Carter Themoquad adjustment - 03/21/10 08:18 PM

It was rebuilt by a shop that has done hundreds. I knew it had to be setup since my engine is far from stock. I just don't remember how since it has been a long while.

Attached picture 5879010-P1010018.JPG
Posted By: ademon

Re: Carter Themoquad adjustment - 03/21/10 08:23 PM

Quote:

What is all this JET WELL chat ? ... is this what you guys have seen lots ? ... I have rebuilt more than my share of TQ's .. but I have only seen that prob once.

Which year/model carbs are prone to this issue ?


i think al the 72 and later ones, i have only rebuilt one and it leaked, its the two small bumpes on the bottom of the bowl the jets screw into the well area. i just checked it by adding water to the bowl when apart and looking for a drip or moisture around the factory sealer.
Posted By: SattyNoCar

Re: Carter Themoquad adjustment - 03/21/10 09:25 PM


I've rebuilt a number of TQ's, and all the ones I've done, you could see the metering rod adjustment screw when the metering rods were up. I can't see yours in the pic (screwed in too far would make it rich). Not conclusive by a long shot, but, one of the first things I'd check.

I've had the leaking wells too, but, it was always on a TQ that was on a car with Lean Burn.
Posted By: LL340Rag

Re: Carter Themoquad adjustment - 03/22/10 01:27 AM

That's what I am looking for. Where are the rod adjustment screws supposed to be?
Posted By: dOc !

Re: Carter Themoquad adjustment - 03/22/10 01:33 AM

That is only ONE screw ...and the height-spec is not "standard" .. it can vary. Do you have a pic of yours?

And is your rich-situation through all ranges of operation ?
Posted By: MY340

Re: Carter Themoquad adjustment - 03/22/10 01:54 AM

Bottom your metering rod tree by turning screw CCW and then turn the screw 1 turn CW just as you see the tree start to raise for stock setting.

1.5 turns out on the idle mixture screws is a good starting point.
Posted By: LL340Rag

Re: Carter Themoquad adjustment - 03/22/10 10:52 AM

Quote:

That is only ONE screw ...and the height-spec is not "standard" .. it can vary. Do you have a pic of yours?

And is your rich-situation through all ranges of operation ?



Where is the one screw on the carb supposed to be. The small one in the center triangle? I know it is not standard. I just need to play around with it. It is rich through everything. It runs nice but is massively rich to the point of having to change my clothes after 30 seconds of running.

Attached picture 5880169-P1010022.JPG
Posted By: a12rag

Re: Carter Themoquad adjustment - 03/22/10 03:03 PM

Hmmmm, is the float level too high ?? Yes, the rod adjustment screw is the one in the "triangle" as you pointed out. When the car is running, vacuum pulls the rods down (with the stepped rods in the jets, this effectively changes the size of the openings (i.e. lean or rich). . . the screw allows adjustment of this . . .

Rather than playing with it too much, is there a shop nearby that has a mechanic that knows carbs (not many of the breed left !!!) and would be able to hook it up to an exhaust analyzer ? Then you know for sure that you are adjusting things correctly.

Is the choke on ? Oh sooo many questions . . . check out the attached link :

http://carburetor.ca/pdf_manuals/Carter/1972TQmanual.pdf

TQ's are great carbs, but really need to be adjusted in sequence . . . happy tuning. . .

Cheers

Mark
Posted By: moper

Re: Carter Themoquad adjustment - 03/22/10 03:38 PM

The metering rod spring hanger (the long arm the rods go on) has a sngle piston in the center. The screw head you see is the top of a long rod that goes downt o the bottom of the baseplate. The lever in the baseplate works like apower valve t force the rods out of the jet, richening the full hrottle mixture to the max the jet and rod will flow whetehr there is vacuum or not. At all other times and throttle openings, the rod hanger is controlled by engine vacuum operating against the step up spring, which is under the piston on the rod hanger. If you engine is not stock, my impression is the factory spring is incorrect and pushing the rods to the rich end of the spectrum all the time. You can adjust that center screw all you want, if the spring isn't properly matched to the combo, you'll be either rich or lean all the time except full throttle.
Posted By: Rug_Trucker

Re: Carter Themoquad adjustment - 03/22/10 04:32 PM

Quote:

What is all this JET WELL chat ? ... is this what you guys have seen lots ? ... I have rebuilt more than my share of TQ's .. but I have only seen that prob once.

Which year/model carbs are prone to this issue ?




Yep I just pop the wells off on any rebuild, restick them. I have pulled some apart that the wells completely drop off. I redo them with JBQuick or regular JB if I'm not in a hurry to put it back into service.
Posted By: LL340Rag

Re: Carter Themoquad adjustment - 03/22/10 08:57 PM

I had gotten it a lot better this morning. Next I need to adjust the float bowl. Then I ran out of gas and had to go to work. I have a shop with a great mechanic that knows TQ's well but the car isn't on the road yet. It's my 71 Demon.
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