valve guides

Hi could someone help me out here. could you explain to me why the valve guides are required. thanks scotsman17

They keep oil from going into the combustion chamber, as well as absorb some of the heat from the combustion chamber so the valve does not runn too hot.

If they are really worn then small amounts of unmetered air can enter the cylinder causing the idle to be rough and give a slightly lean condition.

They are what holds the valve in place. If you didn't have valve guides, the valves would just flop around in a big hole. Massive vacuum leaks, oil burning and pretty severe damage would occur without them.

They ARE the hole into which the valve fits. Without them, there is nothing to keep the valve in place.

Valve guide is to valve as cylinder is to piston.

They really do nothing to keep the valve in place, they are a sleeve that is a different material than the cast head is made out of. Regular cast heads would be too rough a surface for the valves and they would pass oil real quick. They are generally softer and have a better surface finish to aid longevity and oil control. Some are replaceable, some are not. The ones that are are sometimes made of a bronze alloy that tends to be self lubricating for better performance, less friction and improved oil control.

Bob

thanks for the help