There have been some inquires from racers and engine builders regarding the legality of valve seat angle modifications following the 2004 rule change for cylinder head modification in Super Stock, as outlined in the 2004 NHRA rule amendments.

While the valve location and angle must remain stock with a stem angle variance of no more than +/- one degree from stock, the valve seat angle can be changed.

Also, as indicated in the rules revisions, any valve job is acceptable in Super Stock.

Racers may further note in the 2004 NHRA rule revisions, under General Regulations, that the illustration that appears on page 190 of the 2004 NHRA Rulebook only applies to Stock. Therefore valve seat and face angles may be modified in Super Stock.