Divorced Chokes - a few questions

When you first pump the pedal for the day, the choke should SLAM shut when cold, correct?

I think my choke is acting.. well not proper. The car is a bear to get woken up when it hasn't run yet for the day.

88 318 with a 850TQ on top of a Performer, the choke has been replaced with a 4v correct piece instead of the bent and worked 2v one I used when I did the 4v swap. So the spring tension and length of the choke rod should be correct to get the choke to actuate properly upon a cold start.

When cold, you should always push petal to floor and back (a quick snap is all it needs) for choke to reset. On any carbureted car, one should make a practice doing so each and every time you get behind the wheel.

The reset could slam the parts into place but many times it simply pops into place (not a lot of force behind it, but some).

If the air cleaner was off, after choke reset and the cold engine is off, you should be able to push the choke plate (the top moving plate) open to look inside of it, but it will pop closed right back.

Red arrow.

Once engine is started, the choke plate may be still in a closed position, but generally is in a mid-position (not open fully but not closed) and will slowly open fully as engine warms.

That is not to be confused with the fast idle cam. The choke pulls on that cam via linkage, but that cam won’t move until throttle is touched.

It has been my experience, as the choke thermostat coil (the bi-metallic spring) gets older (10-15 years old), it doesn’t move as much as it once did (kinda falls into, and is stuck, in a mid-position). Generally 85% of the time, replacing the Choke thermostat coil (or assembly) will fix most drivability problems.


On that year, there should be a choke heater wire coming from the choke thermostat going to a white 1 inch x 2 inch electric relay (about mid position between choke thermostat and distributor). If that wire is broken off or is not plugged into that white box – that could also be a problem. The white box needs to be plugged in (goes to ignition coil, indirectly, I think).


Often, I find a broken wires) or that white box simply not plugged in.

Note: a few cars have a small round black disk, instead of a flat white box with two plugins on it.
Also make sure that white box/black disk is getting power when engine is on.


If cold drivability still exists, the one needs to remove carburetor from car, and perform all of the adjustments – to the letter. Some of those have twenty different adjustments to it. How well a carburetor works depends on each and every one of those adjustments to be spot on.

Need to check vacuum lines for routing and if hoses are cracked or not.

Check the air heater stove for operation (on left exhaust manifold with black or silver flex tube going

To air cleaner. I haven’t found a bad vacuum motor yet, but the temp sensor on air cleaner base and vacuum hoses I’ve seen hooked up (or not) in error or failed/broken.

Last thing is I would check the base gasket between the Thermoquad and intake. It should be roughly ¼” thick. If one is using a thin gasket or a much thicker gasket, then choke thermostat won’t work very well (already way out of specs).

If you check all of that and still have problems, write back,
BudW

The heater portion won't affect a cold start but the choke will open too slowly without it.
I remember the TQ from tech college way back in '83 and there being 21 adjustments, that must be done in order and as BudW said, they must all be precise. Get one wrong and it'll throw off every adjustment made after that. Tedious is the word I'd use.

I like the Thermoquads.
Just like all of the other carburators out there, these have their own share of problems. Once you know the problem areas, then you are good to go.

The interesting part is I have somewhere between 70 to 90 Thermoquads in my garage, right now. About ½ were purchased/obtained for parts and the other half – well . . . I’m not sure how I ended up with that many - or what exactly I'm going to do with them all.

The ones for parts, I bought so I could “make my own jet kit” – which I hadn’t done yet (in the two decades spent obtaining these gems).

Another interesting part is, currently, I don’t have a vehicle with a 4-bbl on it, yet (will have soon, but not yet).


Not counting the TQ’s in my garage, I may have worked on another couple hundred TQ’s as well - so quite familiar with getting those things set up just right.

The really “fun” ones are when people think they can bend that rod or that tab, without knowing what they are doing, so you end up with a basket case. Those literally take several hours to get back into adjustment.

Almost all TQ's need minor adjustments and it takes me about 1½ to 2 hours just to go through and makes sure everything is adjusted correctly.
If rebuilding a TQ, it takes me about 2 to 3 hours to dissemble, clean, reassemble and adjust it correctly (not counting soak time) total time.
With all of that said, it has been 15 (maybe 20) years sense I have rebuilt a TQ. Other kinds, is a different story.

On top of having a complete shelf system for my TQ’s so none get damaged, I also have about 25-30 other carburetors of various Mopar makes/models.

BudW

My choke thermostat is brand new, and the correct 4bbl one used on the models of the time. The TQ itself is also setup as per a TQ tuning guide I found when putting the carb together. The kit inside as well as the base gasket are new (3k miles). I have the small black disk and resistor looking choke warm-up power. I am fairly certain it is getting power, will check that out. The idle mixtures are set to achieve the best vacuum of 21 in/hg, and the base timing set to 7* BTDC. All new vacuum lines, and no vacuum leaks. Creating one can audibly change the engines running/tone. I do not have the stove pipe in action, as the hot air doors on the air cleaner were busted to begin with, and the stove pipe missing. However, I understand it is "needed" I don't think it is a crucial piece (all the guys with chrome air cleaners, and no pipes).

The reason I ask about the choke, is because sometimes on a cold start (i use that as not a warm engine term, the car is not winter driven) the engine cranks and cranks and needs many pedal pumps to fire off. Obviously the choke hasn't closed. It seems stiff in its motion. but nothing is really bound up, the spring just doesn't push up as forcefully as I think it should.

The 2bbl holley this car had when it was an ESA/ELB car, the spring would SNAP the choke closed on a cold start. Audibly heard from inside the car the click of the choke plate closing hard lol. This one, if it moves it, moves it rather slowly.

From the sounds of it, I think the choke is working like it should be.

You mentioned:

8v-of-fury said:

the engine cranks and cranks and needs many pedal pumps to fire off.

Click to expand...

and that sounds like a different concern these vehicles have – the carburetor fuel bowl is dry and you are waiting for fuel pump to refill the carburetor, before it can fire off.

That happens to my ’86 5th Ave all of the time.

There are several reasons this can happen. A hotter than normal running engine is most likely, the black plastic fuel bowl does lessen the effect of heat – but it still happens.

Another likely cause (which works in conjunction with heat) is fuel evaporates (faster) when hot. If there is a place for fuel vapors to exit easy, it will do so.
Examples are open chrome air filter, the large vent hose going to charcoal canister is left off and so forth.

When you can keep the carburetor as closed as you can (no vapors to leak to outside, or from top of carburetor, if the fuel was to evaporate, it has nowhere to go and condenses back in the fuel bowl.


Another possibility is fuel level is set too low. Also having a weak fuel pump and/or getting air in fuel line somewhere (think cracked rubber hose or rusted line) can affect fuel delivery.


In my case, I replaced the Holley 6280 Lean Burn carburetor with an older Carter BBD. The Lean Burn computer is still on air cleaner and is working the ignition – but for some nexplained reason, it can’t get my carburetor to respond. This carburetor (also) doesn’t have a vapor vent mechanism on it.

After a hard drive or after sitting for two weeks or longer, it will take forever to start because fuel bowl is dry.
After short trips or not so hard drive, it will start right up.


Checking fuel level on a TQ can be done on engine – but is not an easy job. Actually, it is not an easy job period.
The BBD is a lot easier and can also be done on car.

What I’ve been doing is turning off A/C the last mile or so and taking it easy the last bit, after driving it hard/hot - and startups have been easier.
In my case, closing the fuel vapor areas should fix my problem (but my priority has been getting things ready to install big block – so will do that later).

BudW

Hmm yes, that makes some sense. Except I bet if I ran the engine just long enough to "reprime" the fuel system if it were empty, it would do it again the next day lol. I do not think it is an empty float bowl situation, as I can remove the breather for the first start of any day even after the car has sat a month and there will still be good pump shots of the accel pump. I trust I have my float level correct, as when I didn't the car ran like absolute SHIT lol.

Sonething my friend mentioned to me, he said something was wrong because the car shouldn't even need the choke to fire off. Two pumps should be enough to do it for anything but actual cold days. Does he have his idle set REALLY rich if it will start and run really well when cold without the choke?

The accelerator pump system is more “closed” and less likely for fuel to evaporate out of.

Most of the carburetors I have worked on, - you can run the engine out of gas intentionally (disconnect fuel line, start engine and let engine run until there nothing in fuel pump, lines or fuel bowl. After that, you will still have two or three shots of fuel in the accelerator pump system.

I’m only trying to point out there may be other causes to your problem, other than (or in addition to) the choke.

I appreciate it It provides good brain activity when there is a friendly banter back and forth of ideas and thoughts. So thank-you.

I use a normal style air cleaner with only the three vents on the top of the carb being the vents. I think I got it figured out though, it would seem the little clip that goes around the choke-rod was binding ever so slightly and only sometimes.. causing the choke to never set ! LOL I went to make a video to show you what I was talking about, and then I noticed it right away at that time hahaha. Any idea why it seems to like A LOT of pumps to start though, if it weren't a low float situation?

I’ve seen a few bent clips over the years. Also a few missing clips (not sure how they stay in place . . . ) and even tape (etc.) used to hold it together (which doesn’t work well).

What would be wonderful would be to have a sight glass on side of carburetor – to check float level – but I don’t think that will ever happen on a TQ.

Some cars are cold natured and some cars have a mind of its own (Christine, comes to mind).


Removing the carburetor and taking some time to go through all of the settings should help.

BudW

Go to cold start the car today at an ambient of 40F, and raining all day. I give it two pumps, and hold he throttle open just a little bit. IT WAS TOO MANY PUMPS! The engine stuttered to start and finally caught after a few revs, I had flooded it with 2 pumps. This is hugely awesome.

This really tells me I have things very well dialed in, as that is how all the other carburetors in my day-to-day start.. lmao I work as a marine tech, so I do deal with quite a few carbs. None as involved as the TQ tho lol, and they all have electrical chokes and we basically just clean them if we have issues. No tuning/setting up.

ANYWAY. The car probably woulda started with a half pump today just to set the choke up. Thanks for bouncing ideas off of me BudW