Engine Overhaul Manual
Jabiru Aircraft
Pty Ltd
Jabiru 2200 & 3300 Aircraft Engines
This document is controlled while it remains on the Jabiru server. Once this no longer applies the document becomes uncontrolled.
ISSUE
1
2
3
4
5
6 7
Dated : 28/10/2014
Issued By: AS
Page: 79 of 201
L:\files\Manuals_For_Products\Engine_Manuals\Overhaul_Manual\JEM0001-7_Overhaul_Manual_DRAFT_(29_10_14).docx
5.11.5 Valve seats
Top end overhaul:
apply bearing blue to the valve and rotate the valve against the valve seat using
hand pressure only. Remove the valve and inspect for sealing between the valve and the seat
– if there
is not a uniform seal within the limits shown in Figure 90 then the seats will need to be cut and the
valves may also need to be refaced.
Valve seats are cut at 45 degrees for the actual seat and then under and over cut at 30 and 60 degrees
as required to obtain a seat width as shown in Figure 90. In general, try to cut only the minimum amount
from each seat in order to extend the life of cylinder heads.
Figure 90
– Valve Seat Geometry
5.11.5.1 Inspection and repair
Figure 91
– Recessed Valve Seat, Valve Being Cut
The valve face must protrude at least 0.6mm (inlet) or 1.0mm (exhaust) from the face of the combustion
chamber.
Figure 91 (left) shows a valve fitted to a recessed seat. This assembly is unserviceable. To avoid this,
valve seats must be cut as lightly as possible.
Figure 91 (2 right pictures, above) shows a valve / valve seat being cut using a hand grinder and valve
lapping paste on the sealing face.