Some controller types can be field adjusted to help with manifold boost. Two such are the Variable Absolute Pressure Controller and the Density Controller. Examples following:

• To increase manifold pressure turn adjusting screw counterclockwise.
• One full turn should give you one inch.
• Recommend turning counterclockwise 2 full turns, if too much back up slightly.

To adjust density:

• On square adjusting bolt, turn clockwise to increase manifold pressure.
• Approx. 1/4″ turn should suffice.

The latest revision of Lycoming Service Instruction No. 1187 sets forth procedures and required equipment for adjusting density controllers in the field.