Cliff's Quadrajet Parts and Rebuild Kits

Quadrajet Problem Solving => Diagnose a Quadrajet carburetor problem => Topic started by: stevef on April 10, 2011, 11:16:06 AM

Title: Rochester 2 GC nozzle drip
Post by: stevef on April 10, 2011, 11:16:06 AM

To review, I've had difficulty starting the 75 Lemans with a pontiac 350, after it's warmed up. Carb is a Rochester 2 GC that I rebuilt recently due to the starting problem, and it still does it.

To test it, I drove the car about 5 miles to warm it up good, parked it back in the driveway, and turned it off. I blocked open the throttle and with a light down the throat, I observed nozzle drip, a drop from each nozzle about every 15 seconds it seemed.

During the rebuild, I put in a new float and set it to the factory float level specs. I was wondering what I can do to remedy the nozzle drip? Thanks!

Title: Re: Rochester 2 GC nozzle drip
Post by: Toronado on April 11, 2011, 02:00:31 AM

Fuel pressure can be causing it,
check what the pressure running at.

Title: Re: Rochester 2 GC nozzle drip
Post by: stevef on April 11, 2011, 06:12:15 AM

I already checked the fuel pressure and it's well within specs. It has a fuel return line to the tank too, so I don't think it's holding pressure in the line.
I'm going to try lowing the float level 1/16" and see.

Title: Re: Rochester 2 GC nozzle drip
Post by: Cliff Ruggles on April 12, 2011, 04:06:41 AM

"Nozzle drip" is a condition that happens with the engine running at idle speed.  The throttle plates are open far enough to pull some fuel from the main system.

Dripping from the nozzles after shutdown indicates the fuel level in the carb is too high for some reason.  Completely different symptom and cause, etc.....Cliff

Title: Re: Rochester 2 GC nozzle drip
Post by: stevef on April 12, 2011, 11:39:44 AM

Thanks Cliff. That's good to know the difference in terminology. I lowered the float level 1/16, and rechecked for the drips and they were gone, so that problem appears to be cured. At least it should prevent some underhood gas odor, and save a little gas :) .

It didn't cure my starting problem though. So, I just swapped in another distributor with a new control module in it. It's starting good now.

I didn't think it was the distributor at first, since I thought when a module went bad, a car wouldn't run at all. But my car would eventually start and run. Oh well, it was a good learning experience  :) .

Title: Re: Rochester 2 GC nozzle drip
Post by: Cliff Ruggles on April 13, 2011, 02:31:12 AM

Good news on figuring it out.  Sometimes there is more than one problem from more than one source, making troubleshooting difficult, repairs as well.

I'd like to have $1 for every carburetor problem I've fixed where the engine didn't want to idle well when the trans was placed in gear, that was actually a distributor problem!.....Cliff