S27 FE 350 ENGINE
Cylinder Head
14
CYLINDER HEAD
See General Warning on page 10-1.
GENERAL INFORMATION
Test cylinder compression using a standard compression tester. Low compression would normally indicate a problem
in the cylinder assembly such as defective rings, gaskets, etc. Compression should be:
•
Key-Start engines:
Key-start engines are equipped with an automatic compression release valve (ACR). This
valve releases compression pressure at normal cranking RPM, resulting in lower compression. At a normal
cranking speed of 550-600 RPM, the compression should typically be 71 psi. This value could vary slightly
depending on wear of components affecting compression.
•
Pedal-Start engines:
Pedal-start engines are not equipped with an automatic compression release valve (ACR). At
a normal cranking speed of 550-600 RPM, the compression should typically be 156 psi. This value could vary
slightly depending on wear of components affecting compression.
See the Engines and Drivetrain Components, Repair and Rebuild Manual for inspection and repair.
BREATHER VALVE (REED VALVE)
General Information
The function of the breather is to create a vacuum in the crankcase which prevents oil from being forced out of the
engine through the piston rings, oil seals or gaskets. The breather has a reed valve which limits the direction of air flow
caused by the piston moving up and down. Air can flow out of the crankcase, but the one-way reed valve blocks return
flow and therefore maintains a vacuum in the crankcase.
Oil laden air in the crankcase passes through the reed valve and expands into the rocker chamber. In the rocker
chamber most oil separates from the air and drains back to the crankcase. The air passes through a tube and vents to
the intake manifold.
See Engines and Transaxles Manual for inspection and repair.
VALVE CLEARANCE CHECK AND ADJUSTMENT
1.
Check and adjust clearance when the engine is cold.
2.
Turn the crankshaft until the piston is at the top of the compression stroke.
3.
Using a feeler gauge (1), measure the clearance (2) between the adjuster screw (3) and the top of the valve stem
(4)
(Figure 14-2, Page 14-4 and Figure 14-3, Page 14-4)
4.
If necessary, loosen the lock nut (3) and turn the adjuster (6) up or down to adjust the clearance to 0.005 inch
(0.127 mm) for both intake and exhaust
5.
While keeping the adjuster from turning with the screw holder (5) (CCI P/N 1016413), tighten the lock nut (3) to
90 in-lb (10 N·m).
6.
Recheck the clearance on both valves.
2009 FE 350 Maintenance and Service Supplement
Page 14-3
