Intake and Exhaust Valves/Intake and Exhaust Valves 23. Clean valve seats using a wire brush. 24. Inspect valve seats for damage, corrosion, pitting or warped condition. 25. If necessary, cut seats to a 45 degree seat angle using a seat cutter such as JDG507. M36274 -UN-29JAN90 CTM2 (19APR90) 15-9 16, 18, 20 & 24HP Onan Engines M98,2015K,19 -19-08OCT85 AllTractorManuals.com 130495 21. Measure tappet outside diameter. TAPPET SPECIFICATIONS Item New Parts Wear Tolerance -UN-29JAN90 Tappet Diameter 18.99—19 mm 18.90 mm (0.747—0.748 in.) (0.744 in.) If tappet diameter is less than 18.90 mm (0.744 in.), replace tappet. M36272 M98,2015K,17 -19-08OCT85 22.
Measure tappet bore inside diameter and determine tappet clearance (tappet bore I.D. minus tappet O.D.). TAPPET BORE SPECIFICATIONS Item New Parts Wear Tolerance -UN-29JAN90 Tappet Bore Diameter 19.06—19.09 mm 19.15 mm (0.750—0.751 in.) (0.754 in.) M36273 Tappet Clearance 0.04—0.08 mm 0.15 mm (0.0015—0.003 in.) (0.006 in.) If tappet bore diameter exceeds 19.15 mm (0.754 in.), install over-sized tappet or replace cylinder block. If tappet clearance exceeds 0.15 mm (0.006 in.), install over-sized tappet, replace tappet or replace cylinder block. NOTE: The over-sized tappets available are 0.05 mm (0.002 in.) and 0.13 mm (0.005 in.). M98,2015K,18 -19-08OCT85 9