There are ( 2 ) cylinder heads on your 4.0 liter over head valve V6 engine
The Ford 4.0 liter V6 engine ( both the OHV and SOHC ) ( has 2 engine cylinder heads )
( 8 spark plugs ) for your 4.6 liter V8 engine in a 2002 Ford Explorer
For a 1997 Ford Explorer 4.0 liter V6 engine ( EFI and SOHC versions ) ( There are 6 spark plugs )
There are two cylinder heads on a V6 3.1L engine.
2 per cylinder , the 3 valve per cylinder heads were used in the F-150 starting with the 2004 model and I believe in the Ford expedition starting with the 2005 model
The 2009 Ford Explorer has 12 valves.
The 2012 Ford Explorer has 24 valves.
The 2001 Ford Explorer has 12 valves.
The 2011 Ford Explorer has 24 valves.
The 2008 Ford Explorer has 12 valves.
The 2010 Ford Explorer has 12 valves.
The 2004 Ford Explorer has 12 valves.