Flatness of gasketed surface:
Using a straightedge and thickness gauge, check surface at a
total of 6 locations. If distortion limit, given below, is exceeded,
correct gasketed surface with a surface plate and abrasive pa-
per of about #400 (Waterproof silicon carbide abrasive paper):
place 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 re-
duced power output.
Limit of distortion: 0.05 mm (0.002 in.)
Distortion of manifold seating faces:
Check seating faces of cylinder head for manifolds, using a
straightedge and thickness gauge, in order to determine wheth-
er these faces should be corrected or cylinder head replaced.
Limit of distortion: 0.10 mm (0.004 in.)
Valve Springs
Referring to data given below, check to be sure that each spring
is in sound condition, free of any evidence of breakage or weak-
ening. Remember, weakened valve springs can cause chatter,
not to mention possibility of reducing power output due to gas
leakage caused by decreased seating pressure.
ENGINE MECHANICAL (F8D ENGINE)
6A1-37
Item
Standard
Limit
Valve spring
free length
37.09 mm
(1.460 in.)
36.2 mm
(1.4252 in.)
Valve spring
preload
13.3 – 15.7 kg for 32.0 mm
(29.3 – 34.6 lb/1.26 in.)
13.0 kg for 32.0 mm
(28.7 lb/1.26 in.)
