Cylinder Head Inspection
• Remove all carbon deposits from combustion
Do not use any sharp-edged tool to scrape
off carbon deposits. Be careful not to scuff or
nick metal surfaces when decarbonizing. The
same applies to valves and valve seats, too.
• Check cylinder head for cracks on intake and exhaust
ports, combustion chambers, and head surface. Using
a straightedge and thickness gauge, check flatness of
gasketed surface at a total of 6 locations. If distortion
limit is exceeded, correct gasketed surface with a
surface plate and abrasive paper of about #400
(Waterproof silicon carbide abrasive paper): place
abrasive paper on and over surface plate, and rub
gasketed surface against paper to grind off high spots.
Should this fail to reduce thickness gauge readings to
within limit, replace cylinder head.
Leakage of combustion gases from this gasketed joint
is often due to warped gasketed surface: such
leakage results in reduced power output.
Distortion for cylinder head surface on piston side
Limit: 0.03 mm (0.001 in.)
• Distortion of manifold seating faces:
Check seating faces of cylinder head for manifolds,
using a straightedge and thickness gauge, in order to
determine whether these faces should be corrected or
cylinder head replaced.
Distortion for cylinder head surface on intake and
Limit: 0.05 mm (0.002 in.)