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?

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).

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.

Thanks. More work.

did they reseal the jet wells?

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?

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.

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 ?

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.

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.

That's what I am looking for. Where are the rod adjustment screws supposed to be?

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 ?

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.

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

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.

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.