Carb Idle Tube
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Registered User
Joined: Aug 2012
Posts: 39
From: DoD n Stuttgart GE
Carb Idle Tube
Curious....
I am searching for carb stuff and came along this process.
Drilling out the idle screw feed tube.
... drilling the end with a 0.037-inch drill bit
Read more: http://www.highperformancepontiac.com/tech/hppp_0702_rochester_quadrajet_carburetor_tuning/photo_08.html#ixzz257OTHChZ
To get more fuel at idle?
Has anyone else done this?
Comments?
I am searching for carb stuff and came along this process.
Drilling out the idle screw feed tube.
... drilling the end with a 0.037-inch drill bit
Read more: http://www.highperformancepontiac.com/tech/hppp_0702_rochester_quadrajet_carburetor_tuning/photo_08.html#ixzz257OTHChZ
To get more fuel at idle?
Has anyone else done this?
Comments?
Registered User
Joined: Dec 2011
Posts: 7,286
Yes it has been done.
The trick is to fin a drill under 0.040", the smallest number drill commonly available at your local store.
I found a pack of metric micro drills at Harbor Freight which go down to 0.5mm = 0.020" I believe.
The trick is to fin a drill under 0.040", the smallest number drill commonly available at your local store.
I found a pack of metric micro drills at Harbor Freight which go down to 0.5mm = 0.020" I believe.
Connoisseur d'Junque
Joined: Sep 2010
Posts: 21,183
From: The Hudson Valley
You have to look at the bigger picture, Ronz.
A carburetor is designed to mix fuel into the air that passes through it in a certain ratio, depending on conditions.
In theory, you might think that the ratio should always be the same, but there are many reasons why it may be better a bit rich or a bit lean at different times, and those reasons and conditions will vary with different engine designs and specifications.
In the article you referenced, they are talking about modifications for a high-performance engine, which has a hot cam. Because of their more radical cams, engines such as these have low vacuum at low RPMs, such as at idle. With their low vacuum, they are unable to effectively pull enough fuel out of the idle circuit of a stock carburetor, which is designed for a high idle vacuum level. One way of fixing this problem is to open up the idle jets a bit, allowing fuel to pass through more easily, so that more fuel gets to the engine in spite of its lower vacuum.
Unless you are running a radical cam, this has nothing to do with you.
- Eric
A carburetor is designed to mix fuel into the air that passes through it in a certain ratio, depending on conditions.
In theory, you might think that the ratio should always be the same, but there are many reasons why it may be better a bit rich or a bit lean at different times, and those reasons and conditions will vary with different engine designs and specifications.
In the article you referenced, they are talking about modifications for a high-performance engine, which has a hot cam. Because of their more radical cams, engines such as these have low vacuum at low RPMs, such as at idle. With their low vacuum, they are unable to effectively pull enough fuel out of the idle circuit of a stock carburetor, which is designed for a high idle vacuum level. One way of fixing this problem is to open up the idle jets a bit, allowing fuel to pass through more easily, so that more fuel gets to the engine in spite of its lower vacuum.
Unless you are running a radical cam, this has nothing to do with you.
- Eric
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