Valve overlap

[SSDiv6]

Originally Posted by FireSale

OK. I read this revision as "Aluminum heads OK. No billet in modified classes except CS"

2017 revision:
Aftermarket aluminum cylinder heads permitted (no billet) except in CS.

I'll take the car to ETI in March and see. I'm beginning to not care any more.

Back to camshafts.

Dale,
The rule can be confusing.
What the rule change should say is that any aftermarket aluminum head, except billet heads are allowed.
Still, SS/CS class is NHRA approved cast iron cylinder heads only.

Prior to the current rule, it was required to run approved cylinder heads that had an OEM part number.

As applicable to your Mustang, would be the Ford N351 cast iron cylinder head casting.The N351 head, as cast, just with port matching, will outflow the AFR 165 heads by a mile.