[toddallen]

According to service manuals the angles of the seat and valve are ground 1 degree different,Now I have a friend that has a valve grinding set up and insists they should be ground to the same angle, I dissagree I think the engineers that decided this found a reason for it, what do you think? how can I convince my friend if indeed he has misinformation,
thanks

[toddallen]

According to service manuals the angles of the seat and valve are ground 1 degree different,Now I have a friend that has a valve grinding set up and insists they should be ground to the same angle, I dissagree I think the engineers that decided this found a reason for it, what do you think? how can I convince my friend if indeed he has misinformation,
thanks

[yankeeralph]

The purpose of the different angles is to allow a smaller contact surface between the seat and valve. The smaller surface contact with a given set of valve springs will allow the greatest seat load (Pounds per square inch of seat contact. Better seat load corrosponds with better sealing. With both cut at the same angle, the valve will ride flush with the seat angle and result in a lesser quality seal.

[1970cat]

also hellps to "chip" away any carbon buildup , keeping a good seal.

[Bob Eiler]

If your friend has the capability to measure seat and face runout use the same angle for valve face seat. Shop manuals advise using an interference angle because the quality of valve jobs can vary greatly. Pontiac recommends .002 runout for seat and valve. An interference angle is not needed with accurate machine work. I use <.001 for the seat and <.0005 for valve face. I once had fix a valve job on sbc that had .008 seat runout. An interference angle will pound out within 100 miles. Also a 45 degree seat will wedge tighter than a 30 degree seat.