Pontiac 24506031 Valve,Intake

The 231 cu in V6 engine has a significantly different valve mechanism than most GM engines, inasmuch as it does not provide for a valve lash adjustment. If for instance the valve seat on the cylinder head or the valve face is ground it could either increase or decrease the height of the valve stem from the head surface. The stem should be reground to the natural height if the valve and seat have been refinished to an extent where the valve stem end of a smallest size is higher by approximately 0.050 in from the normal position as shown above. The first step is to take off the cylinder head; place it on a clean platform or any flat surface. Insert a suitable spring compressor tool and compress the valve spring in order to have access to the valve spring cap key and then remove the spring as well as the cap. Take out the valve seals and take out the valves and arrange them in the suitable order in a wooden or a cardboard so that the same can be fitted in the machine later. Scrub the cylinder head and examine it for cracks; valves should also be checked for pits or burning around them, or poor contact area; if necessary they may be rebored or replaced; any valve that becomes sharp on the edges once ground should be chucked. The accuracy concerning the valve face angle is at 45°. If the stem has too much end-play in its guide, the valve should be replaced by an oversized one and this can only be done effectively by a dealer or a machine shop. The valve seats should also be trued-up to 45°, which is also best done in a dealer or a machine shop. Following the trueing job, valve should be lapped slightly against the seats using the carborundum paste of wrong grade and suction cup lap to and fro grinding tool with occasional lifting of the valve for the paste redistribution. Slip off the paste and work it over with fine carborundum paste until there is laid on a level circle of grey matte finish and be careful to wipe off all grinding compound. Coat the valve stems and guides with the engine oil and replace the valves as they were earlier. Replace intake valve seals at least and do not replace or install exhaust valve guide seals. Because the valve stem enters the guide with contact below, begin the valve seal over the valve stem, press it down until it rubs on the top of the guide, and install the seal over the valve guide with an installation tool by fitting the seal tightly. Slightly compress the springs when fitting the keepers so that you do not spoil the valve seal through over-compression. Last but not the least, the intake and the exhaust valve springs are to be fitted; place the valve spring, the cap and the cap retainer and fit the cylinder head back again.