So my problem is the choke plate on the carb won't stay in the upright position after the engine warms up. I have to stop every so often, kick the accelerator pedal a couple of times, the engine goes back to normal idle, I drive a bit, and same thing. The RPM boots up to 1500 until I kick the gas pedal again.

1970 C3 (454) LS5, Automatic transmission
Quadrajet # 7040204 FF (divorced choke).

The carb was rebuilt about 3 years ago (no, not by Lars. Unfortunately I live in Canada and Lars does not take on jobs outside the USA). The carb was running fine up until last week.
Any help as to where to start troubleshooting is appreciated.

Tks.

 

Sounds like the rod from the thermostatic coil to the choke mechanism is disconnected. Need pictures of the choke side of carburetor.

 

The rod's connected.

 

Maybe all the dents in the choke coil cover are causing a "drag" and hanging it up? Try getting the dents out and making sure everything inside the cover has plenty of clearance.

 

I ordered a new cover.
I also ordered a new coil in case this one has lost its springiness (if that's a proper word, LOL). Trying to be proactive.

Speaking of cover, is the purpose of the cover to keep the rod from coming out of its place in the coil?

 

Your choke pulloff spring has been disconnected from the pulloff and hooked onto the choke shaft arm - it is assembled wrong. It should look like this:


Once you fix that, verify that the pulloff is, in fact, fully retracting upon engine start - that pulloff is certainly not a new pulloff from a recent carb rebuild.

Also verify that the choke coil rod is providing a positive "upwards push" on the choke rod when the engine is hot. It is highly unlikely that the dented choke coil cover has any effect on the coil operation.

Finally, verify that, when the engine is hot and running, the fast idle cam and counterweight drops all the way down to the carb casting stop under its own weight when you tap the throttle to disengage the fast idle screw from the fast idle cam.

Lars

 

Lars, it's difficult to see the differences from your carb pic to Roger Dodger's... Are you referring to the small spring at the yellow area should go to the slot at the white arrow?

 

I was just about to ask the same thing.
Not to sound ungrateful, and I really appreciate the pic, but it's a bit hard to make out.

 

Enlarge Lar's picture. Looks to me the spring is on the bottom screw not the shaft above it

 

Update;

I picked up my car last week and now the choke plate is locked in the upright position and won't go down. Started it up yesterday morning as usual; pressed the gas pedal to the floor to apply the choke, but before turning the ignition on, I looked to see if the choke was engaged and discovered it was not. Choke plates completely upright, I tried to move them down, no luck. It's like they were locked there. In any event, I started the car after a few cranks and playing with the gas pedal. Here is what the choke side of the carb looks like now:









Question: ^ ^ ^
Which way is the choke coil spring loop for the rod supposed to face, towards the (back) firewall or the (front) radiator?

It's quite a hassle for me to keep bringing the car to the shop as it's a 70 mile round trip plus I have to navigate traffic congestion on the only bridge I have to use to get there and back. Real PITA. So if the problem is relatively easy to fix without removing the carb, I'm willing to give it a try myself and bother you guys in here for any help I may need.

I just received from CC new choke coil spring, coil spring cover and I also ordered a new choke rod and clip. Is there anything else you guys think is needed? Otherwise, I'm sending the carb for a complete overhaul/rebuild. I think I may have found someone here in Canada who appears to know what they're doing.

Thanks.

 

Good grief... If a shop put that together, and supplied that carb, don't ever use that shop again - whoever did that work is an idiot. They never tested or verified their work to make sure it was working..?? Who does that kind of chit?

The choke coil is installed backwards, and the coil is installed wrong. The choke rod needs to PULL DOWNWARDS when the engine is cold. From the appearance in your photos, your coil and rod are pushing upwards.

Be aware that your carb has been commercially rebuilt, and has been assembled with barnyard hardware from uncle Fred's barn. It is likely to have significant problems, far beyond Bubba's bad assembly work on the choke... That is not the same carb as the one shown in your first photos. Did Bubba at the shop supply you with a "rebuilt" carb and take your original one in "exchange?" Go get your original carb back! You've been screwed pretty badly, unfortunately... (I can see different casting numbers on the carb in your photos above versus the numbers on the carb in your photos posted in post #3 - Bubba switched carbs on you... If your carb was an original carb, Bubba just took a $3,000 454 carb from you and sold you a hacked 350 carb worth about $75. Time for a small claims suit.) The 454 carb they took from you is irreplaceable, and the "rebuilt" carb they gave you is total junk.

Correctly installed 1970 divorced choke:


Lars

 

The shop you drive 70 miles to mangled the choke coil cover because they don't seem to know how it's supposed to work.
You should be able to correct this yourself.
Look at post 5 in this thread and maybe get a copy of the 1970 factory manual.
I missed Lars comment but basically the same opinion.
https://www.corvetteforum.com/forums...oke-stove.html

 

There is nothing you can do to correct what they did other than getting your 454 carb back from them and having it professionally rebuilt.

 

The original carb is sitting in a box, waiting for me to find someone who knows what they're doing. Nobody pulled a "switch" on me, I have both carbs. No need for lawyers.
The carb in the second photo is a rebuilt carb I bought and had installed a couple of years ago and is presently on my car. And as I had mentioned, the carb ran well for a while, but it looks like after a few service calls and trying different things to adjust choke/idle/ blah blah blah ...... the guy at the shop fucked it up to the point I'm at now.

But fear not, I'll deal with it. it's my cross to bear. I didn't start this thread to get shitted on, just looking for some constructive help.

The problem is finding people who know how to properly restore. And unfortunately, not everyone has a Lars on their speed-dial. This is where I'm at a loss.

Thanks again.

Cheers!

 

DUDE don't scare me like that!

 

Now now .... it's nothing to be scared about. It's ok, really it is.

 

If it were my car. I would send the original ot Lars and solve the problem. I have a 68 that the previous owner had Lars rebuild the carb. It looks like brand new and functions like new as well. That will be one less problem for you, bolt it on and enjoy your car. Plus, having peace of mind if any more carb problems come up you have Lars' support.

 

Just venting. Nothing more nothing less. It's frustrating, that's all.

 

Yup, Lars was my first choice, a few years ago, actually.
But Lars does not accept jobs outside the USA. Can't say I blame him, must be a logistical/paperwork/shipping nightmare.

 

Thanks to all who have tried to help. I'll use whatever info from this thread and give it a go.