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Fig. 9: Cylinder head bolt torque sequence A.
On 1990-93 Accords, tighten the bolts to 29 ft. lbs. (40 Nm) on the first pass, 51 ft. lbs. (70 Nm) on the second pass, then tighten the bolts to their final torque of 78 ft. lbs. (108 Nm).
Fig. 2: Rocker shaft bolt tightening sequence-1992-95 Preludes and 1990-95 Accords without VTEC.
As part of every major tune-up or service interval, the valve clearance should be checked and adjusted if necessary.
If the valve clearance is too large, part of the lift of the camshaft will be used up in removing the excessive clearance, thus the valves will not be opened far enough. This condition makes the valve train noisy as they take up the excessive clearance. The engine will perform poorly, since a smaller amount of air/fuel mixture will be admitted to the cylinders. The exhaust valves will not open far enough to vent the cylinder completely; retained pressure (back pressure) will restrict the entry of the next air/fuel charge.
If the valve clearance is too small, the intake and exhaust valves will not fully seat on the cylinder head when they close. This causes internal cylinder leakage and prevents the hot valve from transferring some heat to the head and cooling off. Therefore, the engine will run poorly (due to gases escaping from the combustion chamber), and the valves will overheat and burn (since they cannot transfer heat unless they are firmly touching the seat in the cylinder head).
While all valve adjustments must be as accurate as possible, it is better to have the valve adjustment slightly loose than slightly tight, as burnt valves may result from overly tight adjustments.
See Figures 1 and 2
Valve lash must always be adjusted with the engine cold. The head temperature must be below 100°F (38°C). Generally, this means allowing the engine to cool for at least 3 hours after driving. Overnight cold is best. If the valve adjustment is being performed as part of a routine maintenance or mileage service regimen, do it before the engine is warmed up to check timing or idle.
Fig. 1: If the feeler gauge passes with no drag or cannot be inserted, hold the adjusting screw with a screwdriver, then loosen the locknut.
Fig. 2: Turn the adjusting screw to obtain the proper clearance, then tighten the locknut to its proper specification.
Valve location will vary with the type of engine. As a guide, the intake valves always are aligned with the ports or runners of the intake manifold. The exhaust valves align with the tubes of the exhaust manifold.
Adjusting the valves requires positioning No. 1 cylinder at TDC, then rotating the engine to certain other precise positions. Rotate the engine with a socket on the crankshaft pulley. (The crank pulley is the lowest pulley on the engine.) This engine rotation is much easier if the spark plugs are removed before hand, eliminating the compression from the cylinders. Always rotate the engine in a counterclockwise direction as viewed from the pulley end.
If you miss a mark during the rotation, keep going in the same direction until it comes around again. Turning the engine backwards may cause the timing belt to jump a tooth or slacken, risking engine damage when restarted. Remember that cylinder No. 1 is the one closest to the pulley end of the engine.
The engine is at TDC No. 1 if ALL of the following are true:
1990-95 Accord and 1992-95 SOHC Prelude
See Figures 7 and 8
The engines in these cars use 2 intake valves and 2 exhaust valves per cylinder.
Valve clearances for the valves are:
Fig. 7: Valve placement on 1990-95 Accords and 1992-95 SOHC Preludes.
Fig. 8: Camshaft pulley marks on 1990-95 Accords and 1992-95 SOHC Preludes. TDC on the No. 1 cylinder shown.
That should take care of the head bolt torque sequence & spec.Also, rocker assembly torque sequence & specs. Even, valve adjustment how to. Any other questions, please let me know. Thank you.
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