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110 ENGINE 273 MPFI VALVE SEATS • Check valve seat height with respect to cylinder head mating surface. • Replace valve seat inserts if they are worn out beyond specified limit. • Cut exhaust and inlet valve seats with a 45° cutter. NOTE Valve seat must be absolutely faultless and without any chatter marks. • If necessary lap valve seats to a smooth and even finish by using suitable hand pump grinder or a lapping paste and valve itself. • Smear valve seat with carbon blue. Install valve in guide and turn it slowly under axial pressure. • Distance between narrow diameter of valve face to contact line should be minimum. • Check for leakages through valve seat by pouring gasoline on valve head. Gasoline must not seep past valve seat. Valve Seat Inserts • For removing valve seat inserts from cylinder head use a suitable boring machine. Bore old insert thin (about 0.5 mm thickness) and then pry it out. • Alternatively use a suitable turning tool to cut an annular groove into valve seat insert and then pull it out with a suitable puller. In order to avoid damaging machined cylinder head mating surface with crank case, place any soft protective sheetmetal under supports ofpuller. • Measure valve seat insert bore in cylinder head. • If boring and prying is done carefully without damaging valve seat insert bore in cylinder head, fitment of an over size valve seat insert will not be necessary. • All specified dimensions should be strictly maintained to ensure proper interference of valve seat insert in its bore. • Clean the valve seat insert and its bore in cylinder head thoroughly. Just before installation : • Place valve seat insert in a mixture of Methanol and dry ice for about 20-30 minutes to bring its temperature down to - 150°C. • Heat cylinder head to approximately 80°C in water bath. • Install valve seat insert in cylinder head bore quickly by using mallet. • Machine valve seat in cylinder head. VALVE SEAT INSERT THICKNESS INLET EXHAUST 6 mm 6 mm VALVE SEAT INSIDE DIAMETER IN INSERT INLET EXHAUST 28. 7± 0.1 mm 23.5 ± 0.1 mm VALVE SEAT INSERT & BORE DIA. IN CYLINDERHEAD Stage Valve seat insert Valve seat insert bore diameter in outside diameter cyl. Head (mm) (mm) Inlet Normal 34.1 H7 34.1 Z6 Normal 1 34.4 H7 34.4 Z6 Exhaust Normal 31.5 H7 31.55 X7 Normal 1 31.8 H7 31.85 X7