Running rich - HELP?
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3rd Gear
Joined: Jan 2013
Posts: 3
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Running rich - HELP?
Running rich HELP!!
I have a problem with my C3-1968-327. It started running rich and wetting the sparkplugs. I then noticed that one of the Rochester needles was clogged or stuck as it dripped instead of fuming. I rebuilt the carb but that didn't change anything so I bought a new rebuild carb and thought I had it all salved. Nothing changed even if the fumes are now perfect. I have remounted the carb many times to check for vacuum leaks but nothing changes. I have retraced the wires and the firing order and cannot find anything wrong in the ignition. When I hock up an analyzer it gives me a reading of resilient fuel of 2000 ppm on both exhausts when the normal reading should b 200 ppm. Can anybody give me helpful tips on this problem???
Joe from Iceland
I have a problem with my C3-1968-327. It started running rich and wetting the sparkplugs. I then noticed that one of the Rochester needles was clogged or stuck as it dripped instead of fuming. I rebuilt the carb but that didn't change anything so I bought a new rebuild carb and thought I had it all salved. Nothing changed even if the fumes are now perfect. I have remounted the carb many times to check for vacuum leaks but nothing changes. I have retraced the wires and the firing order and cannot find anything wrong in the ignition. When I hock up an analyzer it gives me a reading of resilient fuel of 2000 ppm on both exhausts when the normal reading should b 200 ppm. Can anybody give me helpful tips on this problem???
Joe from Iceland
Race Director
Joined: Jan 2000
Posts: 12,399
Likes: 247
From: San Jose CA
When you rebuilt the carb did you replace the float? What kind of float did you use? Did you adjust it?
The idle circuit on quadrajets is pretty straightforward - the idle air bleeds, idle fuel tube restriction, and idle down channel restriction determine how much fuel will make it to the mixture holes and transfer slots, and the screws determine the final idle mix.
I'd write Lars at v8fastcars@msn.com as well, he can probably help you trouble shoot why it'd suddenly be bad.
For what it's worth, the brass nozzles in the primary venturi should NOT be dispensing fuel at idle. If you are seeing that drip at idle, I'd actually start by turning the idle mixture screws out (richer), as this is a sign that the carb is trying to pull fuel from the main circuit to stay alive. Those nozzles should not come into play for quite a while. You should not see ANY fuel coming out of those nozzles at idle.
The idle circuit on quadrajets is pretty straightforward - the idle air bleeds, idle fuel tube restriction, and idle down channel restriction determine how much fuel will make it to the mixture holes and transfer slots, and the screws determine the final idle mix.
I'd write Lars at v8fastcars@msn.com as well, he can probably help you trouble shoot why it'd suddenly be bad.
For what it's worth, the brass nozzles in the primary venturi should NOT be dispensing fuel at idle. If you are seeing that drip at idle, I'd actually start by turning the idle mixture screws out (richer), as this is a sign that the carb is trying to pull fuel from the main circuit to stay alive. Those nozzles should not come into play for quite a while. You should not see ANY fuel coming out of those nozzles at idle.
Drifting
Joined: Jan 2002
Posts: 1,645
Likes: 11
From: Schaumburg IL
Definitely shoot Lars an email for the paper on rebuilding and/or get the Doug Roe book on rochesters. When the car is warm and idleing, look with a flashlight (no candles) at the primary boosters and see if there is fuel dripping. If so, I say one thing -- float level. Set to Lars paper.
Also, did you by chance us marine epoxy on the well plugs that may be dripping.
finally, most stock GM fuel pumps unless a defective one put out in the 5-6 lb range and should not blow past the needle and seat.
Also, did you by chance us marine epoxy on the well plugs that may be dripping.
finally, most stock GM fuel pumps unless a defective one put out in the 5-6 lb range and should not blow past the needle and seat.
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Verdad Gallardo
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
If you're dripping fuel out of the main discharge nozzles at idle, you have a problem. There should be no fuel at all dripping from the main discharge nozzles. The common problems for this are:
1. Excessive throttle blade opening required to maintain idle speed. This can be caused by a timing problem - inadequate timing advance. Before you ever touch the carb, make sure your timing is correctly set with an operable vascuum advance control unit hooked up correctly. See my timing papers on how to do this. Timing affects carb, but carb does not affect timing. Fix your timing first, and then see how the carb reacts.
2. High Float Level. This can be caused by:
High float
Leaking needle/seat
Stripped seat threads
Defective float
3. If the carb you installed is a commercially rebuilt carb, it has a multitude of internal problems that will cause the dripping issue. Repairing a commercially rebuilt carb will involve fabrication of airbleeds and some significant work - I've done a few posts on those pronblems here on the Forum.
Lars
V8FastCars@msn.com
1. Excessive throttle blade opening required to maintain idle speed. This can be caused by a timing problem - inadequate timing advance. Before you ever touch the carb, make sure your timing is correctly set with an operable vascuum advance control unit hooked up correctly. See my timing papers on how to do this. Timing affects carb, but carb does not affect timing. Fix your timing first, and then see how the carb reacts.
2. High Float Level. This can be caused by:
High float
Leaking needle/seat
Stripped seat threads
Defective float
3. If the carb you installed is a commercially rebuilt carb, it has a multitude of internal problems that will cause the dripping issue. Repairing a commercially rebuilt carb will involve fabrication of airbleeds and some significant work - I've done a few posts on those pronblems here on the Forum.
Lars
V8FastCars@msn.com
