Mounting The Engine - Desert Aircraft DA85 Owner's Manual

Mounting the Engine

The DA85 features a rear induction carburetor that is intended to protrude or breathe through the fire wall.
While mounting and initial setup of the engine and with the carb through the firewall can take some extra
work, this carburetor location provides a stable air environment for consistent high performance, while
greatly reducing carburetor noise.
If the firewall/motor box is to far back, it can be extended using by adding a layer or layers of
aircraft plywood, or extending the motor box with aircraft plywood.
We do not recommend using standoffs or spacers to mount the DA85. Vibration and stress to
the engine case increase when standoffs are used. Damage from using standoffs or spacers will
not be covered under warranty.
If you still elect to use shims or spacers between the rear of the engine and the firewall, make
sure that the mounting faces of all the spacers or shims are flush with the rear of the engine. If
the face of all spacers are not in the same plane or perfectly flush with the rear mounting face of
the motor, the crankcase may be damaged. Again, this will not be covered under warranty.
Make sure the carburetor has adequate clearance near the inlet to allow an unobstructed airflow
into the carburetor. If the carburetor is located in front of a former or firewall, be sure there is at
least 1" (25mm) of clearance from the carburetor inlet. If there is less than 1" clearance, make a
hole larger than the carburetor inlet diameter in the former or firewall.
The throttle arm is tapped for a 2-56 SAE ball link. If you wish, the throttle return spring can be
released or cut on one end, but not removed. Without the spring, vibration will wear and damage
the shaft and carb plate. This wear/damage will allow air and fuel to enter the engine when in the
closed position, resulting in an unreliable idle and erratic throttle control.
The choke lever can be actuated by hand with a small light weight pushrod or by a small servo
behind the firewall. There are two arms on the choke shaft. One is re-moveable and can be
repositioned to give proper geometry for linkage access from the bottom or rear. Do not remove
the detent ball and spring on the choke shaft.
We do not recommend soft mounting the engine as it can cause problems with exhaust systems
and carburetor linkages.
If the carburetor is enclosed, guide tubes pointed directly at each needle can be installed to
allow easy needle adjustments with a narrow screw driver. (See photo)
Make sure firewall and/or motor box are secure.
Check the mounting bolts regularly to insure they are tight.
Needle valve adjustment
guide tubes
L
2
Throttle arm
hoke arms on both sides
C
H