Pontiac 7/16 Rocker Arm Stud Polylock Upgrade/Conversion Kit, 1961-1966 389-421 Heads

7/16 Thread-Grade 8 with Hex nut on shank. Use existing 7/16 rocker balls or add as an option. 7/16 Lock Nuts. Kit includes machined washers to allow for polylock to not bottom out and have room for locking.

***When converting press-in studs holes must be drilled and heli-coils inserted for 7/16 threaded studs-  STUD BOSSES WILL NEED TO BE MILLED, THIS SHOULD BE DONE BY A QUALIFIED MACHINE SHOP***

Comes with ARP-135-7101 with a Thinner Hex because you will need to mill the Stud Boss

Early 389/421 heads with thru stud oiling These studs do not have oil thru holes on certain pre 64 heads, simply use rocker arms and pushrods with oil hole on oil thru stud applications, we also plug the block with 2- 1/8 npt pipe plugs at deck to keep oil away from heads but this may not be mandatory.