So I had my '79 into a shop a couple of months ago.  Paid a boatload of money to have them tune-up the engine including rebuilding the carb.

It was running great when I brought it home.  A day or two later, I noticed the performance slipping.  It was running real rough at idle when I first started up in the morning. 

The most annoying problem was that when I would leave my house, and make the turn out of my neighborhood... the engine would completely bog down when I accelerated.  I noticed that the harder I accelerated, the worse it was.  So I learned that if I accelerate slowly, there would be no problem.

The thing that bugged me was that this never was a problem before I brought it to the shop for the tune-up.  So I took it back to them, telling them my complaints.

I was told that the bogging down is expected when cold because the rear 2 carb chambers are blocked off until the engine warms up and the choke opens. 

First question... is he right?

I asked why this didn't happen before and he couldn't give me an answer.

Second question...  is it possible this wasn't a problem before because the choke was stuck open?

Thanks!

Gotta love this site......Somehow, it's comforting to know the "BIG BOSS" has the same type questions I'd ask .

JR

Adam a rough idle at first start sounds to me like the vacuum choke pull-off is not working or set up right. If it's blowing out black smoke, it's the choke. Does it run fine when it's warmed up? When you acellerate when the motor is cold it will suck the choke closed. boggin the motor down. I'd start there first,

  Dave

"I was told that the bogging down is expected when cold because the rear 2 carb chambers are blocked off until the engine warms up and the choke opens. "
Not exactly.....It's true the rear butterflies will(should) not open until the choke comes off, BUT....that will not cause a "bog", because there's no air going thru them, thus no extra fuel would be needed to keep it from bogging. It just won't have the same power as it does when warm, that's all. I agree that the choke could be the problem, as well as a possibility of the accelerator pump not working. You said if you give it gas slowly, it seems to run a little better. If it's not blowin' a butt-load of black smoke(indicating a closed choke), I would look at the accelerator pump, and the pump check-ball first. It could be that there is some trash that got dislodged in the process of cleaning the carb, and now is stuck somewhere else, which is not a good thing! I'd take it back and make them fix it, or go to someone else who knows how to work on Quadrapukes, if you can find them! Good luck, and let us know what you find out.!
btw...anouther thing.....it could also be a problem with the float level. A 'bog' could be caused by low fuel level.Adams' Apple38457.8332291667

Adam, look at the disc I sent you, or go to Ben's site and look at the rebuild article.  It may help you understand.  It sounds like the pull off is out of adjustment.  You can see that with the bubble gauge.  And no, the secondaries not opening will not make it bog.

This hinges on whether or not it now runs okay warm.  If there is a problem fully warmed up, it will usually be worse when cold and warming up.

The other option is to just drop by my place this summer.

Just thought I'd give you an update...

I sent an email to the owner of the shop, which is County Corvette in West Chester, PA, by the way.  I explained the situation and that I expect they should get it back to proper running condition.

The next morning, I got a call from the mechanic there that worked on my Vette.  He seemed surprised that I was still having trouble, even though it had left there in the same condition I am complaining about.  He suggested that maybe the Accelerator Pump has gone bad, which he said was replaced when he rebuilt the carb.  So if I bring it back, he could try that.

At any rate, I'm taking it back to them this Wednesday.  I'm hoping and expecting that I will not have this problem any more when I get it back!

Adam

Make sure you point out the other problems...heater hose hanging down below the frame & at least one vaccum hose not replaced. Glad you decided to fight back. People like Adam are to nice & get taken advantage of by give-a-s*** mechanics. Maybe forums like this and others can send a message to these clowns...check your work before you give it back to the customer. Talk is cheap it's the end result that counts.

Alan

Keep up posted.

Similar situation happened to me. took the car to reputable Carb rebuilders. Car ran like a bat out of hell for about 3 days.Then all of a sudden it was a hard start in the mornings and the car would hesitate when accelerating from a stop. Hot or cold  did`nt seem to matter.

Have to bring it back in Tommorrow.

I wouldn`t normally miond but they are not open on weekends and close at 5pm. Qiute an inconvenience.However they gave no excuses and offered to check it out right away.

Update:

I dropped it back off at County Corvette yesterday. Of course, I couldn't show them the problem, since it has to be cold to do it.  But they said that they'll try some other things, like the accelerator pump, to see if they can get it right. 

It has also been running really crappy, but of course, seemed to be running ok while I was there!

As I left, the president of the shop took it out for a drive.

I really hope they can get this right!

I'll keep you posted...