Valve lash is the gap that exists between the rocker arm adjusting screw and the butt-end of the valve stem. Valve lash should be checked (and adjusted, if necessary) in Samurais every 15,000 miles (24,000 km) or 12 months--whichever comes first--using the procedure below. Use a quality thickness gauge set to make your measurements. Proper clearances are as follows:

Tools and parts

Setting Valve Clearance (lash)

Make sure the key is removed and the vehicle is in neutral.

Remove the blow-by gas hose from the cylinder head cover.

Remove the cylinder head (valve) cover and gasket. If you're careful, you may be able to re-use the gasket. (See the Samurai FAQ if you have trouble getting this cover off).

Caution: Reposition the distributor to the proper location if you moved it to remove the valve cover!

Remove the rubber plug from the ignition timing check window. This plug is located on the bell housing on the driver's side of the engine (left-hand drive vehicles).

Double-check to be sure the key is removed from the ignition. Viewing the crank from the front of the vehicle, turn the crank clockwise using a 17mm wrench. Align the line just below the "T" mark stamped in the flywheel with the "match mark" (the 90° corner forming part of the hole in the bell housing). This indicates when the #1 cylinder is at Top Dead Center (TDC).

Note: Cylinders are numbered starting from the front of the vehicle.

Remove the distributor cap and ensure the the rotor is positioned as pictured. If it is not, rotate the crankshaft exactly one full turn, aligning the marks once again.

Caution: Intake valves are on the side of the head nearest the carburetor, exhaust valves on the side nearest the exhaust manifold. Do not reverse the adjustments between intake and exhaust sides, or you'll be looking at a valve job.

Note: To set the clearances properly, use a box-end wrench to loosen the lock-nut only slightly, and leave the wrench in place. Then turn the adjusting screw while your feeler-gauge blade is inserted between the screw and the valve stem. You should adjust the screw until a slight "drag" is felt when you try to slide the blade. Once the proper adjustment is made, hold the screwdriver tightly and retighten the lock-nut, keeping the blade of the feeler-gauge in place. Double-check for a slight drag on the blade and readjust if necessary. It's better to set valve lash slightly loose than set it too tight.

Once everything is correctly positioned, set the intake valve clearances on cylinders #1 and #2 and the exhaust valve clearances on cylinders #1 and #3.

Rotate the crank exactly one full turn clockwise, then set the intake clearances on cylinders #3 and #4 and the exhaust clearances on cylinders #2 and #4.

Double-check that all lock nuts are tight, and that you haven't left anything sitting on the cylinder head.

Put your distributor cap back on.

Put your old gasket back in place (or use a new one) and then the valve cover.

Caution: Immediately reposition the distributor to the proper location (and retighten the distributor bolt) if you moved the distributor to replace the valve cover!

Torque the valve cover bolts to spec. Do not over-tighten the valve cover bolts or you'll be one unhappy camper. You'll either strip out the aluminum head, or you'll have a valve cover that leaks like a sieve.

Reconnect the blow-by gas hose to the cylinder head cover.

Put the rubber plug back in the ignition timing check window hole in the bell housing.