I see a lot of people not going to 1.60 valves on the 416 heads, they are staying with the 1.50. By going to a 1.60, what is the difference going to be vs a 1.50 valve? Is it even a question worth asking?

 

In a nutshell, more valve = more area to flow through = better. Factory heads from this era needs all the exhaust help they can get.

1.94/1.6 valves are what I used in my P/P'd 416's.

 

Especially for a high exhaust breathing motor such as a nitrous or blower motor.

 

what about port velocity? someone else said they used smaller valve for port velocity

 

You worry about port velocity a lot more on the intake side than the exhaust. Factory exhaust ports need all the help they can get.

The exhaust side is more or less shoved past the valve. Rather than the intake, where if there is too much oprt volume, the incoming air charge can "deaden" (lose velocity) because the port volume is too large. Exhaust exits the past the valve first. There's really nothing to lose velocity over.

 

As long as you can squeeze them in without shrouding or clearance issues, go bigger.

I've generally been an advocate (check the archives) of using larger valves and less lift to achieve flow. You can always open the larger valve wider if you want. More valve face perimeter area will generally provide more flow than opening the same valve wider.

 

And choose a dual profile cam with extra lift and duration on the exhaust eccentric.