Dodge Colt/Challenger/Conquest/Vista 1971-1989 Repair Guide

Valve

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ADJUSTMENT



Models Without A Jet Valve


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Fig. Fig. 1 Adjusting the valve clearance on models without a jet valve

Valve clearance is adjusted with the engine stopped. When adjusting the valves cold, after the engine has been rebuilt or a valve job done on the cylinder head, proceed as follows:

  1. Adjust the valves in the order as shown in hot adjustment-Step 8.
  2.  
  3. Turn the crankshaft pulley to bring the piston to top dead center (TDC) of the compression stroke of the cylinder being adjusted. Loosen the two rocker adjusting screw locknuts.
  4.  
  5. Using a 0.08mm feeler gauge for the intake and a 0.18mm gauge for the exhaust, turn the adjusting screw until the clearance is correct.
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  7. Tighten the locknuts to 7-9 ft. lbs.
  8.  

The normal valve clearance adjustment, or final adjustment after the above initial cold adjustment, is performed as follows. To adjust the valves:

  1. Run the engine until it reaches normal operating temperature and then turn it OFF.
  2.  
  3. Remove the air cleaner. Pull the large crankcase ventilation hose off the front of the air cleaner. Disconnect the two smaller hoses, one goes to the rear of the rocker arm cover and the other to the intake manifold.
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  5. Loosen and remove the nuts and one bracket which attach the air cleaner to the rocker arm cover.
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  7. Lift the bottom housing of the air cleaner off of the carburetor and, with it, the hose coming up from the exhaust manifold heat stove.
  8.  
  9. Unsnap the spark plug wires from their clips on the rocker arm cover.
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  11. Loosen and remove the two rocker arm cover bolts. The rear bolt is a crankcase ventilation fitting, so you will have to use a deep socket or a box wrench.
  12.  
  13. Carefully lift the rocker arm cover off the cylinder head. Using a 5 / 16 " allen socket (1597cc) or a regular socket (1994cc) and a torque wrench, make sure that the cylinder head bolts are all tightened to 58-62 ft. lbs. on 1597cc engines, 72-79 ft. lbs. on 1994cc engines.
  14.  
  15. Hot valve clearance is 0.15mm for the intake valves and 0.25mm for the exhaust.
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  17. Turn the crankshaft pulley to bring the piston to top dead center (TDC) of the compression stroke on the cylinder being adjusted. See step 8. Both valves will be closed at this point and the rocker arms will be resting on the heel of the camshaft lobe (the round side, not the egg-shaped side).
  18.  
  19. Loosen the two rocker arm adjusting screw locknuts.
  20.  
  21. Using the correct thickness feeler gauge, turn the adjusting screw until the gauge just snaps through the valve stem and the rocker arm.
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  23. Proceed to adjust the valves of each cylinder. Remember to bring each piston to TDC.
  24.  

The importance of correctly setting the valve clearance cannot be overemphasized. The clearance must be right or peak performance and efficiency will never be realized. Loose valve clearances will result in excessive wear and valve train chatter; tight valve clearance will result in burnt valve seats.

  1. Apply non-hardening sealer to the rocker arm cover gasket. Always use a new gasket.
  2.  
  3. Install the cover, hoses, spark plug wires and the air cleaner and remaining components. Tighten the rocker arm cover bolts to 4-5 ft. lbs.
  4.  
  5. Start the engine and check for leaks.
  6.  

1978 and Later with Jet Valve


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Fig. Fig. 2 Jet valve location



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Fig. Fig. 3 Adjusting the valve clearance on models with a jet valve



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Fig. Fig. 4 Exhaust valve closing chart



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Fig. Fig. 5 Tighten the screw until a slight drag is felt on the gauge

The 1985 and later Vista and late model Conquest engines have automatic lash adjusters incorporated in the rocker arms of the intake and exhaust valves. These valves are not adjustable. The Jet Valve is, however, adjustable in the same manner as other engines.

A jet valve has been added to the combustion chamber (US models). Its adjuster is located on the intake valve rocker arm. The jet valve must be adjusted before the intake valve adjustment is done.

  1. Start engine and allow it to reach normal operating temperature.
  2.  

Do not run engine with rocker arm cover removed, oil will be sprayed on to the hot exhaust manifold.

  1. Shut OFF engine and remove the rocker arm cover and all spark plugs.
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  3. Turn the crankshaft clockwise until the timing marks (TDC) are aligned. No. 1 piston should be at top dead center (TDC). When No. 1 piston is at TDC, the following valves can be adjusted: No. 1 intake, exhaust and jet valve. No. 2 intake and jet valve. No. 3 exhaust. Watch the valve operation on No. 1 cylinder while turning the crankshaft to close the exhaust valve and have the intake valve just begin to open. This places the No. 4 cylinder on TDC of its firing stroke and permits the adjustment of following valves: No. 2 exhaust. No. 3 intake and jet valve. No. 4 intake, exhaust and jet valve.
  4.  

On 1981 and later front wheel drive models with the K engine (1597cc) a crankshaft pulley access hole is located on the left side fender shield. Remove the covering plug and use a ratchet extension to turn the crankshaft when adjusting the valves.

  1. Jet valves must be adjusted before the intake valve. To adjust the jet valves:
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    1. Loosen the intake valve locknut and back off the adjustment screw two or more turns.
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    3. Loosen the locknut on the jet valve adjusting screw. Turn the jet valve adjusting screw counter clockwise and insert a 0.15mm feeler gauge between the valve stem and the adjusting screw.
    4.  
    5. Tighten the adjusting screw until it touches the feeler gauge.
    6.  


The jet valve spring is weak, be careful not to force the jet valve in.

    1. After adjustment is made, hold the adjusting screw with a screwdriver and tighten the locknut.
    2.  


  1. Proceed to adjust the intake and the exhaust valves on the same cylinder as the jet valve you finished adjusting and move on to the next cylinder.
  2.  

 
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