This is the largest recommended intake valve when using the stock valve seat. 26lb at .815 and coil bind at .425. The stock valve seat will need to be replaced with a larger valve seat (Part Number 6148Y). This valve is top quality and has a radius-type keeper groove. Will fit stock valve guide. Use Part Number ADJ-1046 with ADJ-1057 spring or Part Number ADJ-1047 HP valve spring retainers with the 711421 spring. The use of a ADJ-1051 lash cap is also required. These intake valves are normally paired with exhaust valve ADJ-1126.