What am I doing wrong with my carb?
Thread Starter
Racer
Joined: Apr 2004
Posts: 472
Likes: 0
From: Hartland WI
What am I doing wrong with my carb?
I recently bought a brand new Holley Street Avenger 670 carb and intalled it on my 72. I've been trying to get the idle set right and I'm having issues. I have HEI ignition with an adjustable vacuum can connected to the ported part of the carb. I tested timing and I have 20 initial and 38 all in at about 3600 rpm. When warmed up the car will idle at about 650 rpm. It almost stumbles at this rpm so I would like to get it up to about 800-900 rpm. When I start turning the idle screw nothing happens for about 1/4 turn or so then all of a sudden it will jump up to about 1200rpm. I can't set the idle anwhere in between. What am I doing wrong? Is my vacuum advance kicking in? Do I need to adjust the vacuum can connecting the carb to the distributor? Any ideas?
Safety Car
Joined: Dec 2004
Posts: 4,071
Likes: 0
From: San Diego CA
Originally Posted by Vette Rx
I recently bought a brand new Holley Street Avenger 670 carb and intalled it on my 72. I've been trying to get the idle set right and I'm having issues. I have HEI ignition with an adjustable vacuum can connected to the ported part of the carb. I tested timing and I have 20 initial and 38 all in at about 3600 rpm. When warmed up the car will idle at about 650 rpm. It almost stumbles at this rpm so I would like to get it up to about 800-900 rpm. When I start turning the idle screw nothing happens for about 1/4 turn or so then all of a sudden it will jump up to about 1200rpm. I can't set the idle anwhere in between. What am I doing wrong? Is my vacuum advance kicking in? Do I need to adjust the vacuum can connecting the carb to the distributor? Any ideas?
Race Director
Joined: Sep 2004
Posts: 11,874
Likes: 263
From: Arlington Va Current ride 04 vert, previous vettes: 69 vert, 77 resto mod
you know timing has alot to do with getting the carb set correctly.....before you kill yourself on the carb setting make sure your timing is working properly in all aspects including the mechanical and vacuum advance.....and yes try both ported and unported vacuum onthe vacuum can and see how the car runs....not if it idles faster but see if it runs better.....i think you have a timing issue to resolve
Melting Slicks
Joined: Jan 2005
Posts: 3,028
Likes: 0
From: Madison Ms
First question.....Why are you setting initial timing with the vac hooked up? You wonder why you have idle problems? Pull the vac totally and plug it. Now get your timing to be safe at around 10* BTDC. Now adjust your idle........you will have to adjust again after you hook the vac up if it's on Manifold vac.
Also......you should be on manifold, not ported.
Also......you should be on manifold, not ported.
Thread Starter
Racer
Joined: Apr 2004
Posts: 472
Likes: 0
From: Hartland WI
Originally Posted by MsVetteMan
First question.....Why are you setting initial timing with the vac hooked up? You wonder why you have idle problems? Pull the vac totally and plug it. Now get your timing to be safe at around 10* BTDC. Now adjust your idle........you will have to adjust again after you hook the vac up if it's on Manifold vac.
Also......you should be on manifold, not ported.
Also......you should be on manifold, not ported.
