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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:
- The TDC mark on the flywheel or flex plate is aligned with the pointer in the timing inspection window at the rear of the engine. The TDC mark is generally white; it is never red
- The distributor rotor is pointing at cap terminal or plug wire No. 1. Mark the cap with the corresponding wire numbers, then lift the cap check the rotor position
- The alignment marks on the camshaft pulley are positioned as indicated in the individual procedure
- The rocker arms for at least one of the valves on cylinder No. 1 is loose; the points or lobes of the cam are not putting pressure on the rocker arms.
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:
- Intake: 0.009-0.011 in. (0.24-0.28mm)-0.10 in. (0.26mm) preferred
- Exhaust: 0.011-0.013 in. (0.28-0.32mm)-0.012 in. (0.30mm) preferred.
Fig. 7: Valve placement on 1990-95 Accords and 1992-95 SOHC Preludes.With the ignition OFF, remove the valve cover. Set the engine to TDC No. 1 cylinder. The UP mark on the camshaft pulley should be at the top of the pulley. The two grooves on the side of the pulley should both be visible and aligned with the surface of the cylinder head. The distributor rotor points to No. 1 terminal or wire.
Fig. 8: Camshaft pulley marks on 1990-95 Accords and 1992-95 SOHC Preludes. TDC on the No. 1 cylinder shown.Check the clearance on all the valves for cylinder No. 1 with a flat feeler gauge inserted between the tip of the valve and the contact surface of the rocker. The gauge should pass the gap with slight drag. If the gauge passes with no drag or cannot be inserted, adjust as follows:
Rotate the crankshaft 180 degrees (the camshaft will turn 90 degrees). One of the grooves in the pulley is now vertical and aligned with the indented mark on the timing belt cover. The UP mark is now at the exhaust side and the distributor rotor points to terminal or wire No. 3. Check all the valves for cylinder No. 3, repeating the adjusting steps previously described as necessary. Rotate the crankshaft 180 degrees. Both grooves on the cam pulley are visible and aligned with the head surfaces. The distributor rotor points to terminal or wire No. 4. The UP mark is upside down or at the bottom of the cam pulley. Check all the valves for cylinder No. 4, repeating the adjusting steps previously described as necessary. Rotate the crankshaft 180 degrees. One groove on the pulley is again vertical, aligned with the indentation on the timing belt cover. The UP mark is at the intake side. The distributor rotor points to terminal or wire No. 2. Check all the valves for cylinder No. 2, repeating the adjusting steps previously described as necessary. Reinstall the valve cover.
- Loosen the adjusting screw locknut.
- Turn the adjusting screw to obtain the proper clearance.
- Hold the adjusting screw in position and tighten the locknut. Correct locknut torque is 14 ft. lbs. (20 Nm). After the locknut is tightened, recheck the clearance and readjust as necessary.
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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