Idle should be between 500 to 750 RPM.
Keep the tires inflated to proper specs. Idle less, drive slower.
Should be at least 10 at idle. 25 at idle would be better.
On the driver's side of the F 150 carb, there should be the linkage for the throttle. On the linkage there should be a set screw that you can turn to adjust the engine idle.
# 1 cylinder is at the front by the radiator on the Ford 300 cubic inch straight 6 cylinder
Idle is computer controlled and is not adjustable.
Chain if you are asking about a 300 Cu In 6 cylinder Ford.
For your Ford 4.9 liter / 300 cubic inch inline six cylinder engine : ( the # 1 cylinder is at the FRONT of the vehicle )
there should be 9 total
The 240 cubic inch straight 6 cylinder is ( 6 degrees BTDC ) The 300 cubic inch straight 6 cylinder is ( 10 degrees BTDC ) The 300 cubic inch straight 6 cylinder with manual transmission in California is ( 6 degrees BTDC )
# 1 cylinder on your 300 cubic inch ( 4.9 L ) straight 6 is the FRONT CYLINDER
The idle speed is computer controlled. If the idle is too low, there is a problem with a ssensor or the idle speed motor.
For the 2.0 4 cylinder it should be 9-13 psi, with a minimum of 13 psi deadhead pressure. With the 2.8 liter 6 cylinder it should be 5.5 to 6.5 psi at idle, there is no deadhead specification. Deadhead pressure is pressure at idle with the return line pinched off.