Air box and the AFP fuel servo

Adapting Van’s FAB air box to the AirFlow Performance Fuel Servo:

(Note. Some engine builders use the Silverhawk EX and others use the Airflow Performance)

Contributed by Bill Gill

Van’s FAB air box was designed to be installed with the Precision fuel servo and requires some modifications to adapt to the AirFlow fuel servo. The thick mounting flange was cut off of the air box, enlarging the hole to allow it to fit over the fuel servo as shown below.

It would have been easy if this was all there was to it…no such luck.

Additional material was removed from the air box and a flange was fabricated. The fuel servo was covered snuggly with Saran wrap to protect it and serve as a release. The air box was then secured at the top to the lower inlet floor. This allowed the air box to be positioned correctly. Fiberglass strips about 1.5 inches wide were prepared and applied to the air box outlet and over the Saran wrap on the fuel servo. Once the fiberglass/epoxy cure was complete, the air box was removed and several layers of fiberglass lay-ups were applied to achieve the desired thickness. The inside dimension of the flange may need to be “trued-up”. This can be accomplished using a wood plug (circle) about 1 inch thick with a slightly smaller diameter than the outside diameter of the fuel servo. Attach sandpaper to the outside edge of the wood plug using spray adhesive and fabricate a means to rotate the wood circle as it is inserted into the flange that was fabricated on the air box. This is not a hard task, but it does take some time. The following photos illustrate the process.

Adding additional layers of fiberglass and creating a relief to eliminate interference with the starter.

In position…the flange has a lip incorporated to prevent the Breeze clamp from sliding off. The effectiveness of the starter relief is visible in the upper-left portion of the photo. The starter is a Sky-Tech 149-NL.

Three slots were cut into the flange to allow the Breeze clamp tighten the flange onto the fuel servo.

This view is shown with Van’s 60-amp alternator installed. I later installed the 60-amp alternator from PlanePower which required cutting another relief into the air box.

Bottom view

View with PlanePower alternator installed and fuel hose connected – a relief was cut into the FAB air box for each.