Replacing Valve Guides

Valve guides are a press fit in cylinder heads and should be removed and installed with an appropriate drift. When new valve guides are pressed into cylinder heads, they may close up slightly and the ends may become burred, therefore, after new guides are in place they should be checked and reamed, if necessary, to obtain a correct fit. Use a 5 16 in. reamer figure 3B-10. Lapping Valve Face and Seat for the intake guide and a 11/32 in. reamer for the exhaust valve guide.

It is of prime importance that valve guides fit tightly in cylinder heads. If original guide or new standard guide is not a tight press fit, an oversize guide must be installed. Valve guides are available .001 and .002 in. oversize. When a valve guide is removed and a new guide installed, it is not likely to be concentric with valve seat. If a valve guide is not concentric or true with seat, leakage and burning of valve may result, or valve may break due to cocked seating and deflection of valve stem. Therefore, it is especially important after installing new guides that seats be carefully refaced to make them concentric with guides and assure perfect alignment and matching of valve face and valve seat. See "Refacing Valves and Valve seats."


To install valve assemblies in cylinder head, reverse the disassembly procedure. Apply a light coat of oil to valve seats and stems. Be careful to insert marked valves (18) in their respective guides (19). Carefully seat lower valve spring collar (17) over valve guide. Install springs (16 and 15) and upper collar (14). Compress valve springs with Valve Spring Compressor, Part No. 96600-36. Position keys (13) in valve key groove using grease to hold them in place and slowly release compressor tool until keys are correctly locked in groove (see Fig. 3B-8).

Position spacer (11) in countersunk hole in rocker arm cover. Install marked rocker arms (10) in their respective cover location. Compress spring (9) and position spring between rocker arm and washer. Apply a light film of oil to rocker arm shaft (8) and insert in cover assembly. Examine spring ends to be sure they are square with washer and rocker arm. Install and securely tighten acorn nut and washer (7), shaft screw and new "O" ring (6). Check rocker arm action to make sure it is not binding.

Carefully clean top of cylinder head and rocker arm cover faces with a clean rag. Apply a thin coating of aluminum paint to cylinder head face and position rocker arm cover on cylinder head. Install rocker arm cover screws (4) with flat washer under head of each screw. Screws must be tightened evenly to attain a tight joint. First turn them snug; then tighten each one, 1/8 or 1/4 turn at a time until all are securely tightened.


To install the cylinder head assembly, reverse the order of disassembly. Clean top of cylinder and cylinder head faces and wipe them off with a clean rag. Apply a light coat of engine oil or grease to both sides of a new gasket and position gasket on cylinder face.

Turn engine over so cylinder tappets are at their lowest position and install cylinder head, push rods and push rod covers in one operation. Install push rods in their original position in cylinder head. Be sure push rods register in tappet screw sockets at bottom end and in push rod sockets at upper end. Register oil line (3) in head and crankcase connection.

Install cylinder head bolts with flat washers under head of each bolt. Bolts must be tightened evenly to attain a tight joint. First turn bolts snug, then tighten each of them 1/8 or 1/4 turn at a time with a torque wrench until all are tightened to 65 ft-lbs. Follow same procedure for both cylinder heads. Make sure rubber sleeves arc in place and tighten oil line nuts (2).

Figure 3B-11. Adjusting Tappets Revised: 10-65

Before installing carburetor, replace intake manifold rubber "O" rings. Assemble "O" rings on manifold and then slip carburetor assembly into position aligning the hole in carburetor support bracket with top center crankcase stud. Just snug up stud nut. Carefully square manifold face with cylinder head intake port face and slip rubber "O" ring onto its seat. Insert and tighten two manifold clamps. Tighten crankcase stud nut securely.

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