Lycoming YO-233-B2A Maintenance Manual page 187

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YO-233-B2A Engine Maintenance Manual

TEO-540-A1A Engine Maintenance Manual

Use a 6-point deep recess socket to install the spark plug in the engine cylinder head with a

new gasket. A new gasket must be installed whether the spark plug is new or is acceptable

and being reused.

Thread the spark plug by hand into the engine cylinder head within one to two threads of the

gasket. If the spark plug cannot be screwed in this far, clean the cylinder or spark plug

threads.

Rotate the socket to tighten the spark plug in place.

When the B-nut thread makes contact with the spark plug threads, push the ferrule against the

spark plug while turning the B-nut clockwise.

Continue rotating the B-nut until it seats and is finger-tight.

While holding the spark plug lead ferrule stationary, tighten the B-nut an additional 1/8 turn

with the correct size open end wrench.

Torque the spark plug to 35 ft.-lb (47 Nm).

Torque to 5/8-24 head nuts to 80 to 90 in.-lb (9.2 to 10.4 Nm).

Torque the 3/4-20 head nuts to 110 to 120 in.-lb (12.7 to 13.9 Nm).

February 2021

FAILURE TO INSTALL A NEW SPARK PLUG GASKET ANY TIME A

SPARK PLUG IS INSTALLED CAN RESULT IN INCOMPLETE

SEALING OF THE COMBUSTION CHAMBER, LOSS OF SPARK PLUG

HEAT TRANS, SPARK PLUG OVERHEATING, POSSIBLE

REIGNITION/DETONATION AND INTERNAL ENGINE DAMAGE.

NEVER INSTALL A SPARK PLUG THAT HAS DROPPED ON THE

FLOOR.

HOLD FERRULES WHILE TORQUING THE SPARK PLUG COUPLING

NUT TO PREVENT TWISTING CONDUIT OR CABLE.

74-20

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