Jeep CJ/Scrambler 1971-1986 Repair Guide

Valves and Springs

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Fabricate a valve arrangement board to use when you remove the valves, which will indicate the port in which each valve was originally installed (and which cylinder head on V6 and V8 models). Also note that the valve keys, rotators, caps, etc. should be arranged in a manner which will allow you to install them on the valve on which they were originally used.

REMOVAL



See Figures 1, 2, 3, 4, 5, 6 and 7

All Except the 4-134 Exhaust Valves
  1. The head must be removed from the engine. In all but the 4-134, all the valves are in the head. In the 4-134, just the intakes are in the head. The exhaust valves are in the block.
  2.  
  3. Remove the rocker arm assemblies.
  4.  
  5. Using a spring compressor, compress the valve springs and remove the keepers (locks). A small magnetic tool will help you with this.
  6.  
  7. Relax the compressor and remove the washers or rotators, the springs, and the lower washers (on some engines). Keep all parts in order.
  8.  



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Fig. Fig. 1: With the valve spring compressed, you can remove the valve keepers



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Fig. Fig. 2: There are two keepers, be sure to remove them both



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Fig. Fig. 3: Close up view of the valve keepers, as with all valve train parts, keep them in order



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Fig. Fig. 4: Once the keepers are remove the spring can be removed from the valve stem



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Fig. Fig. 5: Remove the O-ring from the valve stem



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Fig. Fig. 6: You can remove the valve stem seals at this time



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Fig. Fig. 7: You can now pull the valve out of the cylinder head

4-134 Exhaust Valves
  1. Remove the attaching bolts from the side valve spring cover. Remove the side valve spring cover and gasket.
  2.  
  3. Use rags to block off the three holes in the exhaust chamber to prevent the valve retaining locks from falling into the crankcase, should they be accidentally dropped.
  4.  
  5. Using a valve spring compressor, compress the valve springs only on those valves which are in the closed position (valve seated against the head). Remove the valve spring retainer locks, the retainer, and the exhaust valve spring. Close the other valves by rotating the camshaft and repeat the above operation for the remaining valves.
  6.  
  7. Lift all of the valves from the cylinder block. If the valve cannot be removed from the block, pull the valve upward as far as possible and remove the spring. Lower the valve and remove any carbon deposits from the valve stem. This will permit removal of the valve.
  8.  

INSPECTION AND REFACING



See Figures 8, 9, 10, 11, 12, 13, 14 and 15

  1. Clean the valves with a wire wheel.
  2.  
  3. Inspect the valves for warping, cracks or wear.
  4.  
  5. The valves may be refaced if not worn or pitted excessively.
  6.  
  7. Using a valve guide cleaner chucked into a drill, clean all of the valve guides. Check the valve stem diameter and the guide diameter with micrometers. Valve guides on the 4-134 are replaceable. On the other engines, the guide must be reamed and an insert pressed in, or they may be knurled to bring up interior metal, restoring their diameter. Oversized valve stems are available to compensate for wear.
  8.  
  9. Install each valve into its respective port (guide) of the cylinder head.
  10.  
  11. Mount a dial indicator so that the stem is at 90° to the valve stem, as close to the valve guide as possible.
  12.  
  13. Move the valve off its seat, and measure the valve guide-to-stem clearance by rocking the stem back and forth to actuate the dial indicator.
  14.  
  15. In short, the refacing of valves and other such head work is most easily done at a machine shop. The quality and time saved easily justifies the cost.
  16.  
  17. Inspect the springs for obvious signs of wear. Check their installed height and tension using the values in the Valve Specifications Chart in this section.
  18.  



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Fig. Fig. 8: Critical valve dimensions used when checking valves



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Fig. Fig. 9: Checking stem to guide clearance with an dial indicator



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Fig. Fig. 10: Checking valve stem diameter with a micrometer



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Fig. Fig. 11: Roll the valve stem on a flat surface to check for flatness



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Fig. Fig. 12: Completely clean the old gasket material off of the head



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Fig. Fig. 13: A wire brush on a drill will speed the cleaning process, be sure to wear safety glasses



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Fig. Fig. 14: Check the cylinder head for flatness on the diagonal, using a feeler gauge and straightedge



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Fig. Fig. 15: Check the cylinder head for flatness across it surface, using a feeler gauge and straightedge

REFACING



Using a valve grinder, resurface the valves according to specifications in this section.

All machine work should be performed by a competent, professional machine shop.

Valve face angle is not always identical to valve seat angle.

A minimum margin of 1 / 32 in. (0.8mm) should remain after grinding the valve. The valve stem top should also be squared and resurfaced, by placing the stem in the V-block of the grinder, and turning it while pressing lightly against the grinding wheel. Be sure to chamfer the edge of the tip so that the squared edges don't dig into the rocker arm or cam.

LAPPING



See Figures 16 and 17

This procedure should be performed after the valves and seats have been machined, to insure that each valve mates to each seat precisely.

  1. Invert the cylinder head, lightly lubricate the valve stems, and install the valves in the head as numbered.
  2.  
  3. Coat valve seats with fine grinding compound, and attach the lapping tool suction cup to a valve head.
  4.  

Moisten the suction cup.

  1. Rotate the tool between your palms, changing position and lifting the tool often to prevent grooving.
  2.  
  3. Lap the valve until a smooth, polished seat is evident.
  4.  
  5. Remove the valve and tool, and rinse away all traces of grinding compound.
  6.  



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Fig. Fig. 16: Lapping the valves by hand



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Fig. Fig. 17: Home made valve lapping tool

VALVE SPRING TESTING



See Figures 18, 19 and 20

Place the spring on a flat surface next to a square. Measure the height of the spring, and rotate it against the edge of the square to measure distortion. If spring height varies (by comparison) by more than 1 / 16 in. (1.6mm) or if distortion exceeds 1 / 16 in. (1.6mm), replace the spring.

In addition to evaluating the spring as above, test the spring pressure at the installed and compressed (installed height minus valve lift) height using a valve spring tester. Spring pressure should be plus or minus 1 lb. of all other springs in either position.



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Fig. Fig. 18: Testing the valve spring pressure



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Fig. Fig. 19: Checking the valve spring for squareness



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Fig. Fig. 20: Checking the valve spring height

INSTALLATION



  1. Coat all parts with clean engine oil. Install all parts in their respective locations. The spring is installed with the closely wound coils toward the valve head. Always use new valve seals.
  2.  
  3. Use a spring compressor to install the keepers and slowly release the compressor after the keepers are in place.
  4.  
  5. Release the spring compressor. Tap the end of the stem with a wood mallet to insure that the keepers are securely in place.
  6.  
  7. Install all other parts in reverse order of removal.
  8.  

 
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