idle adjustment

[tjvending]

My 72 chevy truck 350, auto has been cutting off on me at red lights when idling. How do I make an adjustment for this?

TJ

[68_chop_top]

On the driver's side of the carb behind the thottle linkage, adjustment screw. Position the screwdriver (could be flat tip, phillips, or torq) from the front and rotate clockwise. Should idle in drive about 600 rpm.

[tjvending]

I have a holley 750 carb....

TJ

[piecesparts]

Automatic or manual tranny?

What is your present idle set at right now?

[tjvending]

Automatic, Not sure , I don't have a tach at the moment

TJ

[piecesparts]

Well, you want the idle adjustment made with the truck in gear to get the torque converter engaged with the engine. Set the idle speed at about 700 RPM (with the truck in gear). I actually run my idle speeds at a little higher, just to make sure that the engine is holding it's own.

A couple things that I would do FIRST: 1) Adjust the fuel/air mixture screws by using a vacuum gauge---not by ear. Connect the gauge to the intake manifold and pick the first screw and turn it in to get the "ZERO" setting, then turn slowly outward until you get the HIGHEST vacuum signal on the gauge. Now do the opposite screw and adjust it until you get the maximum vacuum reading on the gauge. Go back and do this again to ensure that the setting is at it's optimum. When that is done--turn the fuel/air mix screws inward an 1/8 of a turn---YOU ARE DONE. Now look at your timing on the engine. What is you rtiming set at? Try setting the initial timing at 12 to 15 degrees advanced and see if the whole engine runs better. (Don't forget to disconnect the vacuum line from the distributor, first)

Now see if your truck faulters at a stop light, or see if you can keep from spinning the tires at each light.