26
Hangar 9 P-51 PTS Mk II Assembly Manual
Step 4
Close the throttle to the idle position and have a helper hold
your airplane.
Step 5
Attach the glow driver.
Step 6
Turn the engine over using an electric starter. The engine
should fire within seconds of applying the starter.
Step 7
Allow the engine to idle for 30 seconds. Adjust the throttle
trim if necessary to achieve a constant slow idle.
Step 8
With the glow driver still attached and a helper securely
holding the airplane, advance the throttle smoothly to full
throttle. The engine will transition to full rpm.
Step 9
Reduce the throttle to idle and remove the glow driver.
NEEDLE LIMITERS
In some conditions: Due to high altitudes, extreme
temperatures, etc., it may be necessary to slightly adjust the
idle and high-speed needle valves. The high- and low-speed
needles have limiters that prevent over-adjustment.
If your engine starts from the above procedure, but won’t
reliably continue to run with the glow driver removed, follow
the steps below.
Low-Speed Needle Adjustment
High-Speed Needle Adjustment
The needle valves come preset from the factory. Extreme conditions
may require some minor adjustments. Note that the needle adjustment
range is limited, preventing adjustment beyond the practical range.
STEP 1: HIGH-SPEED NEEDLE ADJUSTMENT
With the engine running, advance the throttle to full throttle
while a helper securely holds your airplane. Carefully pinch
and release the fuel line to temporarily restrict the fuel flow.
Caution
: Do not reach over the propeller while the
engine is running.
Correct
: If the high-speed needle adjustment is correct,
the engine will increase rpm slightly (about 300 rpm) and
then die.
Too Rich
: If the engine increases a lot (1,000 rpm or
greater), the high-speed needle is too rich and must be
leaned or turned clockwise.
Too Lean
: If the engine doesn’t increase rpm and simply
dies, the high-speed needle is lean and must be richened or
turned counterclockwise.
STEP 2: LOW-SPEED NEEDLE ADJUSTMENT
The low-speed or idle needle valve, included with the
SetRight
™
assembly, is preadjusted at the factory for best
performance. It may be necessary to fine-tune the low-speed
adjustment using the following procedure:
Step 1
Start the engine and let it warm up, prior to attempting any
adjustments. Make sure that the high-speed adjustment
process is complete before attempting to adjust the low-
speed needle valve.
Step 2
Close the throttle slowly. You will adjust the low-speed
needle setting by rotating the SetRight adjustment bar
clockwise to lean the engine and counterclockwise to
richen the engine.
Caution
: Do not attempt to adjust the low-speed
needle valve while the engine is running.
Step 3
The fuel mixture should be adjusted as follows: The fuel
mixture is too rich if, when opening the throttle rapidly, the
engine emits smoke and “stutters” or “stumbles.” Correct
this by rotating the SetRight adjustment bar clockwise in
small increments. Continue this process until the engine
transitions smoothly from low rpm idle to high rpm without
hesitation upon opening the throttle rapidly.
Step 4
The fuel mixture may be too lean if the engine stops at the
lowest idle position or it stops when the throttle is rapidly
opened from the idle position. Correct this by rotating
the SetRight adjustment bar counterclockwise in small
increments until the engine transitions smoothly without
hesitation upon opening the throttle rapidly from idle.
