Holley Carb Idle Ajustment Problem
Thread Starter
Burning Brakes
Joined: Aug 2007
Posts: 1,084
Likes: 8
From: Illinois
Holley Carb Idle Ajustment Problem
The holley carb on my 71 was recently restored. My problem is the idle for my 350/330hp is supposed to be set at 700 and should idle about 400 rpm above that when cold for the first 20 seconds or so because of the CEC solenoid. I can not set the idle less than 1000 rpm even when the idle screw is backed all the way out. What gives? Idle needs to be 700 rpm. Thanks.
Thread Starter
Burning Brakes
Joined: Aug 2007
Posts: 1,084
Likes: 8
From: Illinois
I am not a carb expert so anyone giving advise will have to keep it simple and thoroughly explain what I should check. I thought all you had to do was turn the idle screw and the idle went up or as you turned it the other was the idle went down until it would kill out on you.
Am I wrong on this?
Am I wrong on this?
Race Director
Joined: Dec 2004
Posts: 15,022
Likes: 2
What is the carb number? Choke? Just a guess, but maybe the fast idle setting on the choke is not set right. If it is engaged, no amount of adjustments on the main idle setting is going to make any difference.
Pro
Joined: Jun 2005
Posts: 660
Likes: 4
From: Fredericksburg VA
My guess would be that you have too much air coming in on the secondary side of the carb and this is not allowing your primary idle adjustment to function properly.
Not sure how simple I can make it but I will try. Over the years I have found that after a carb has been rebuilt and is displaying your same symptoms it is the idle speed adjustment on the secondary side. This is when most state “But there is no adjustment on the secondary’s just the primaries”. To see the screw and adjust it you need to take the carb off the car and turn the carb over. Recessed in the base plate is a screw that adjusts the opening of the secondary throttle blades. Now the setting is a little more difficult vs. the primary side. You will need a 3x5 card to use as a gauge. If you look down the venturies (hole where the throttle blades are) you will see a small slot about 1/8” long and only about a hair wide. You need to open or close using the Secondary Idle Screw so that when you place the 3x5 card on the butterfly you will just start to see the slot. As a side not you ideally should have the same amount of slot showing on both the primary and secondary side.
Hope this helps and does not confuse you more.
Not sure how simple I can make it but I will try. Over the years I have found that after a carb has been rebuilt and is displaying your same symptoms it is the idle speed adjustment on the secondary side. This is when most state “But there is no adjustment on the secondary’s just the primaries”. To see the screw and adjust it you need to take the carb off the car and turn the carb over. Recessed in the base plate is a screw that adjusts the opening of the secondary throttle blades. Now the setting is a little more difficult vs. the primary side. You will need a 3x5 card to use as a gauge. If you look down the venturies (hole where the throttle blades are) you will see a small slot about 1/8” long and only about a hair wide. You need to open or close using the Secondary Idle Screw so that when you place the 3x5 card on the butterfly you will just start to see the slot. As a side not you ideally should have the same amount of slot showing on both the primary and secondary side.
Hope this helps and does not confuse you more.
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Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
The CEC solenoid is not supposed to make the engine idle faster when it's cold. That's the job of the choke. The CEC is supposed to stop dieseling when you shut the engine off and engage the TCS to supply vacuum advance when the engine temp is above 180 and below 230 and the transmission is in third or fourth gears.
You need to set your initial idle using the minimum idle screw to 400 rpm or the lowest rpm the engine will continue to run at with the CEC disconnected then connect the CEC and set the idle to 700 using the plunger on the CEC. Turn it clockwise to lower idle and counterclockwise to raise it.
cc
You need to set your initial idle using the minimum idle screw to 400 rpm or the lowest rpm the engine will continue to run at with the CEC disconnected then connect the CEC and set the idle to 700 using the plunger on the CEC. Turn it clockwise to lower idle and counterclockwise to raise it.
cc
Last edited by CCrane65; Aug 24, 2009 at 09:50 AM.
Thread Starter
Burning Brakes
Joined: Aug 2007
Posts: 1,084
Likes: 8
From: Illinois
The 1971 is different from the 1972. "All 1971's have high idle for 30 seconds regardless of engine temperature." This is due to the CEC or TCS and occurs even if ambient temperature is not cold enough to set the choke.
Safety Car
Joined: Apr 2000
Posts: 3,802
Likes: 61
From: Wichita KS
Your problem is that you are trying to set your idle using only the minimum idle screw and not incorporating the CEC solenoid.
cc
Sorry Paul, I lost track of the fact that you are the OP.
Last edited by CCrane65; Aug 24, 2009 at 02:06 PM. Reason: Fix response for OP not third person.
Instructor
Joined: Jan 2008
Posts: 208
Likes: 0
From: McDonough GA
The slot shd have .030" to .040" or so showing as I recall.
That wacky slot.
My guess would be that you have too much air coming in on the secondary side of the carb and this is not allowing your primary idle adjustment to function properly.
Not sure how simple I can make it but I will try. Over the years I have found that after a carb has been rebuilt and is displaying your same symptoms it is the idle speed adjustment on the secondary side. This is when most state “But there is no adjustment on the secondary’s just the primaries”. To see the screw and adjust it you need to take the carb off the car and turn the carb over. Recessed in the base plate is a screw that adjusts the opening of the secondary throttle blades. Now the setting is a little more difficult vs. the primary side. You will need a 3x5 card to use as a gauge. If you look down the venturies (hole where the throttle blades are) you will see a small slot about 1/8” long and only about a hair wide. You need to open or close using the Secondary Idle Screw so that when you place the 3x5 card on the butterfly you will just start to see the slot. As a side not you ideally should have the same amount of slot showing on both the primary and secondary side.
Hope this helps and does not confuse you more.
Not sure how simple I can make it but I will try. Over the years I have found that after a carb has been rebuilt and is displaying your same symptoms it is the idle speed adjustment on the secondary side. This is when most state “But there is no adjustment on the secondary’s just the primaries”. To see the screw and adjust it you need to take the carb off the car and turn the carb over. Recessed in the base plate is a screw that adjusts the opening of the secondary throttle blades. Now the setting is a little more difficult vs. the primary side. You will need a 3x5 card to use as a gauge. If you look down the venturies (hole where the throttle blades are) you will see a small slot about 1/8” long and only about a hair wide. You need to open or close using the Secondary Idle Screw so that when you place the 3x5 card on the butterfly you will just start to see the slot. As a side not you ideally should have the same amount of slot showing on both the primary and secondary side.
Hope this helps and does not confuse you more.
