Lycoming Wide Deck and Narrow Deck Engines

Applicability: Lycoming O-360 and IO-360

Download PDF: Lyc-wide-and-narrow-deck-engines.pdf

Wide Deck and Narrow Deck Lycoming Engines

Lycoming O-360 and IO-360

Both the 0-360 and IO-360 Lycoming engines were manufactured in a standard and wide deck configuration. To identify these engines, the serial number on the wide deck engine will have an A after the dash number in the serial number. Serial numbers that do not have an A after the dash number are the standard or narrow deck engines.

In looking at the engines, the standard deck has nuts that holds the cylinder to the case are internal wrenching nuts with a hold down plated under the nuts.

The wide deck engines use a standard hex nut with no hold down plates.

The cylinders on a standard deck are lighter, with the case being heavier in this area. This is the reason for the hold down plates on the nut. The wide deck uses a heavier cylinder with the area at the case where the cylinder bolts on being lighter.

Cylinders and cases are not interchangeable. There would be differences in baffle attach and spacing