MODELS AFFECTED: All Lycoming opposed series aircraft engines in Table 2.
TIME OF COMPLIANCE: When installing new rings, pistons, valves and cylinders.
REASON FOR REVISION: Added IO-390-D series to Seal and Gasket set section and Table 2, Updated IO-360-A3B6D and IO-360-C1F part and kit numbers in Table 2, Updated low compression 0-235 series.
NOTICE: Incomplete review of all the information in this document can cause errors. Read the entire Service Instruction to make sure you have a complete understanding of the requirements. This Service Instruction identifies part numbers for pistons, rings, cylinders and valve combinations currently available for use in Lycoming engines in Table 2.
A CAUTION: CHROME PLATED PISTON RINGS (IDENTIFIED BY THE LOWERCASE LETTER “” AFTER THE PART NUMBER) ARE USED IN PLAIN OR NITRIDED STEEL CYLINDER BARRELS. BUT NEVER IN CHROME PLATED BARRELS. SERIOUS ENGINE DAMAGE WILL OCCUR IF CHROME PLATED PISTON RINGS ARE INSTALLED IN CHROME PLATED CYLINDER BARRELS.
NOTICE: Chrome plated cylinder assemblies and kits containing chrome plated cylinders are no longer available from Lycoming Engines. However, compatible piston and ring combinations used with chrome plated cylinders are still available and identified herein.
NOTICE: For replacement piston rings, there could be different piston ring combinations for cylinders with different materials use for the barrel. Engine models that have serial number suffix “A” or E” are built with crankcase configurations for wide cylinder base mounting flanges, and consequently must be assembled with “wide deck” cylinders. Engines with no serial number suffix require “narrow deck” cylinders. Refer to the latest revision of Lycoming Service Letter 220 for additional information on differences between Narrow Deck and Wide Deck Engines.
SEAL AND GASKET SET SECTION
* – If choked chrome cylinder assemblies are used in any of the engine applications in Table 2, the compression ring gap must be increased to 0.045/0.055 inch (1.143 to 1.397 mm) which is the same for nitrided cylinder assemblies. Refer to the latest revision of SSP-1776, Table of Limits.
NOTICE: IN TABLE 1, PISTON RINGS LISTED IN THE PISTON RING PART NUMBER AND ALTERNATE PISTON RING PART NUMBER COLUMNS ARE INTERCHANGEABLE, AND CAN BE INSTALLED ON EACH APPLICABLE ENGINE OR INCLUDED IN CYLINDER KITS IN ANY COMBINATION. TABLE 2, UNDER OIL REG. RING LISTS ONLY ONE PART NUMBER, FOR FULL PART NUMBER INFORMATION REFER TO TABLE 1.
– O-320, IO-320 (low compression) – Kits having a suffix “A” employ heavy piston pin
P/N LW-13445. Plugs unchanged. Interchangeable in complete engines sets only.
– VO, TVO-435 – Kits with P/N having a suffix “A” employ heavy piston pin P/N LW-
13445 (1) and plugs P/N 77856 (2). Interchangeable in complete engine sets only.
♦ – 05K21272 Kit is for use with P/N 71265 and P/N 71266 high lift rocker assemblies to be
used with P/N 77134 camshaft assembly. New engines serial number L-425-37 and up.
Rebuilt engines – Built after 12-14-66.
** Piston P/N 76172 is replaced by piston P/N 14C28324 and is available for purchase at
Scotts Bell – phone: 1 + (507) 665-4064, Fax 1 + (507) 665-0038