Pontiac 12617048 Valve, Exhaust

Valve job is a task that must be left to professionals because of its intricate nature and specific tools and equipment required in handling the valves, valve seats and valve guides. The head can be removed by a home mechanic who can then disassemble it, clean and inspect it before reassembling it for delivery either to a dealer service department or an automotive machine shop where it will get its actual service work done. This inspection will help the mechanic to understand the condition of the head and valvetrain components so they know what work and new parts are needed when dealing with an automotive machine shop. Then, the dealer service department or automotive machine shop will remove the valves and springs, recondition or replace the valves and valve seats, recondition the valve guides, check and replace the valve springs, rotators, spring retainers and keepers as necessary, replace the valve seals with new ones, reassemble all these components including checking that installed spring height is correct. In case it is warped, cylinder head gasket surface is resurfaced too. After having Valve Job from a professional one would notice that Head comes out like New. On its return to the engine however, it should be cleaned again to remove any metal particles or abrasive grit that may still be remaining from either of two instances; from valve service or head resurfacing operations not yet rinsed off. All oil holes and passages should have compressed air blown through them if available.

Check the heads of the valves for pits, burns particularly on the exhaust valves and check the valve seating. If pitting is very minor it can be corrected by valve grinding the seats and the valves using coarse and fine valve grinding paste. To grind the valves, rub some carborundum paste of relatively large grain on the seat face and use suction grinder for the valve head using semi-rotary movement; once in a while, lift the valve head to let the paste spread evenly. When you get a smooth flat surface on the valve seat as well as on the valve face, remove the paste and wash it, then apply fine carborundum paste on the both surfaces and operate the valve lifting it up and turning as desired. For this purpose, it is possible to use a light spring under the valve head. When on both sides there is a continuous line of light grey matte finish the grinding process is said to be over. If there is deep pitting and burning-the valve must be refaced by the dealer and the seat recut; in case after refacing the head edge of the valve is worn down to the specified norms the valve must be changed. Free all carbon from both the valve head and stem and be certain that no grinding compound is in the ports or the valve guides. Scrub the valves and seats with a rag soaked in solvent, and then with a fresh clean rag; retire the valves and, if possible, use an air line to blow out any shooting from the valves, guides and ports.

Conducting the inspection allows for assessment of the condition of the head and valve train components, ensuring awareness of necessary work and new parts when engaging with an automotive machine shop.