81 Carb Adjustment Question

[chevyaddict]

Hi All;
I purchased a rebuilt carb and it works GREAT except for one small issue and my Haynes manual doesn't give me enough information on carb adjustment to fix this. Here is what its doing - I suspect its a choke adjustment issue.

When the car is warm and I try to start it (tried all sorts of ways - no pumping pedal, hold pedal down, no touching pedal, etc) it floods - too much gas is being dumped in from somewhere. It takes a long time to start and I have to rev it up for about 30 seconds to get all the extra gas cleared out. Of course, all the while, black smoke is pouring out of it. After I burn up the extra gas - runs great. When its cold it starts perfect. Its as if the choke is still trying to work even when the car is warm.

So do you guys agree that the choke is operating when warm? The idle isn't any higher though when its warm so.... ?? Could it be something else? Any advice would be appreciated! I purchased from a reputable rebuilder so I feel confident its just an adjustment issue somewhere.

 

[Peer81]

What exactly do you mean by "it floods"? Does the fuel poor out the top of the carb into the secondairies or can you see the fuel being higher then normal?

Is it doing any better with the airfilter unit removed?

You can check the choke by removing the toplid of the aircleaner and see when hot if the choke valve is fully open. Even when the engine is not running (when hot) the choke valve should remain fully open.

Greetings Peter

 

[chevyaddict]

No no...no massive flooding. I only know its a slight flooding situation because of the behavior of black smoke and the hard start problem. In fact, it won't start unless I hold the throttle down to allow sufficient air in to mix with the extra fuel. If I don't do that it will just continue to turn over. No change with air filter unit on or off.

Define "choke valve" please. The choke butterfly is wide open when warm but I'm guessing that is not the "valve". Are you talking about the vacuum unit on the side? How do I know if its open or closed?

 

[SPANISHVETTS]

Hi Dawn,

Is it a Holley?

I have had problems with Holley's leaking - inside, out side, everywhere.

Also could be a float issue. It could be overflowing just enough to flood on a hot start but not enough to give any problems once the engine is running.

Good luck,

Igeaux

 

[Yoda]

,

Why not call the carb rebuilder? Or if you bought it locally take it over and see what he thinks

Just a thought

Spanishvette... if it is a stock carb it would be a Quadrajet E4ME

The GM Shop Manual (ST-364-81) Chapter 6C has a very indepth E4ME Adjustments/Rebuild section

Bud

 

[chevyaddict]

Hi Dawn,

Is it a Holley?

I have had problems with Holley's leaking - inside, out side, everywhere.

Also could be a float issue. It could be overflowing just enough to flood on a hot start but not enough to give any problems once the engine is running.

Good luck,

Igeaux

No its a quadrajet but that float issue is a great idea and an easy thing to fix. Its a brand new rebuild which always need a little adjustment. I'll try that! I just have to figure out HOW to adjust the float on a quadrajet as I imagine its different than a holley

 

[6880 Mike]

This might help. Covers the electronic Q-Jet.

 

[Peer81]

No no...no massive flooding. I only know its a slight flooding situation because of the behavior of black smoke and the hard start problem. In fact, it won't start unless I hold the throttle down to allow sufficient air in to mix with the extra fuel. If I don't do that it will just continue to turn over. No change with air filter unit on or off.

Define "choke valve" please. The choke butterfly is wide open when warm but I'm guessing that is not the "valve". Are you talking about the vacuum unit on the side? How do I know if its open or closed?

By choke valve I meant the butterfly over the primairies. If its fully open then there is max air comming into the carb. So I think no choke problem.

You can find Lars his pages on setting up the float the correct way. On later (like 81 models) the float isn't so high as on previous models. But you need to take off the airhorn to get to the float and reset it.
You can also ask Cliff Ruggles what he thinks is the problem.

Greetings Peter

 

[chevyaddict]

Wanted to let you guys know that it was a clogged fuel charcoal canister that was the problem - not the new carb!