How do you turn up the idle in a 1979 Pontiac Bonneville?

The 1979 Pontiac Bonneville, like most cars of that era, likely uses a fast idle cam or a manual idle speed adjustment screw on the carburetor to control idle speed. There isn't a single "turn this knob" solution; it depends on what kind of carburetor it has (Rochester Quadrajet was common, but others are possible). Here's a breakdown of how to approach this, emphasizing safety and caution:

1. Identify Your Carburetor: Look at the carburetor itself. Knowing the specific model (e.g., Rochester Quadrajet, Carter, etc.) will help in finding precise instructions. A picture would be immensely helpful if you can provide one.

2. Locate the Idle Speed Adjustment:

* Fast Idle Cam (for cold starts): This is a lever or cam on the carburetor that raises the idle speed when the engine is cold. It's usually connected to a thermostatically controlled choke mechanism. You *should not* adjust this unless your idle is too low when the engine is cold and the choke is fully engaged. Improper adjustment can lead to stalling or poor cold starting.

* Idle Speed Screw: This is a screw, often with a spring, usually found on the side of the carburetor. Turning it clockwise generally increases idle speed, counterclockwise decreases it. This is the primary adjustment for idle speed when the engine is warmed up.

3. Adjusting the Idle Speed Screw (if necessary):

* Warm up the engine: Let the engine run until it reaches normal operating temperature.

* Locate the screw: Refer to your carburetor's manual or a diagram specific to your carburetor model.

* Small adjustments: Turn the screw very slightly (1/8th to 1/4th of a turn at most). Wait a few seconds for the engine to respond.

* Check the RPM: Use a tachometer (highly recommended) or listen carefully for the engine's speed. Aim for the manufacturer's recommended idle RPM (usually found in your owner's manual or a repair manual). A typical range might be 600-800 RPM.

* Repeat: Make small adjustments until you achieve the desired idle speed.

4. Important Considerations:

* Vacuum Leaks: A vacuum leak can cause a low idle. Check all vacuum hoses for cracks or loose connections *before* adjusting the idle speed.

* Choke Issues: A malfunctioning choke can also affect idle, especially when cold.

* Professional Help: If you're uncomfortable working on your carburetor, take your car to a qualified mechanic. Incorrect adjustments can damage your engine or carburetor.

* Emissions: Altering the idle significantly can affect your vehicle's emissions.

Disclaimer: Working on a carburetor requires mechanical skill and understanding. Incorrect adjustments can cause serious damage to your engine. If you are not comfortable performing this task, seek the assistance of a qualified mechanic. This information is for guidance only and does not constitute professional advice.