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Cylinder Head Overhaul
*For reference only.


NOTE: Minor cracks between valve seats or between seat and spark plug thread are acceptable. Cracks may not exceed .019" (.50 mm) in width. Cracks may not extend beyond first coil of plug thread.

Valve Springs

Compress spring retainer and springs. Remove keepers, and release spring compressor. Remove retainer and both inner and outer springs. Ensure springs are of equal length. To install, reverse removal procedure.

Valve Guides

Measure valve stem-to-guide clearance with dial indicator pointer on head of valve. Rock valve back and forth and note reading. Maximum clearance is .047" (1.20 mm). If guides are to be replaced, securely mount head in drill press with combustion chambers down.

Carefully use step drill to remove shoulder of valve guide. Avoid cutting head or valve guide boss. Using drift, tap out remaining guide toward combustion chamber side. Install new guide with drift, from side opposite combustion chamber. Ream guides to fit valve stems.

Valves

Check valve dimensions. Minimum length from stem tip to face is 4.823" (122.50 mm). Valve margin must not be less than specification.

CYLINDER HEAD SPECIFICATIONS
Application
Specification
Intake Valve Seat Angle
45
Intake Valve Seat Width
.055-.098" (1.40-2.50 mm)
Exhaust Valve Seat Angle
45
Exhaust Valve Seat Width
.055-.098" (1.40-2.50 mm)
Intake Valve Guide I.D.
.315" (8.00 mm)
Intake Valve Guide Oil Clearance
.047" (1.20 mm)
Exhaust Valve Guide I.D.
.315" (8.00 mm)
Exhaust Valve Guide Oil Clearance
.047" (1.20 mm)
Push Rod Tube Length
7.6" (194 mm)
   
VALVES & VALVE SPRINGS SPECIFICATIONS
Intake Valve Face Angle
45
Intake Valve Head Diameter
1.575" (40.00 mm)
Intake Valve Length
4.823" (122.50 mm)
Intake Valve Minimum Margin
.020" (.50 mm)
Intake Valve Stem Diameter
.314" (7.97 mm)
Exhaust Valve Face Angle
45
Exhaust Valve Head Diameter
1.340" (34.00 mm)
Exhaust Valve Length
4.823" (122.50 mm)
Exhaust Valve Minimum Margin
DO NOT machine; hand lap valve only
Exhaust Valve Stem Diameter
.3508-.3512" (8.91-8.92 mm)

 

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