Variable cam timing/phasing.

[Digital Boy]

	Okay, I'm still a layman when it comes to phasing, etcetera.  To 
my simple, confused mind, I can understand how varying the rate at which 
the camshaft spins, in regards to the crank, can change the timing of the 
valves opening and closing, but not the lift and duration of the valves.
	Wouldn't having control over the lift and duration be more 
critical than phasing change? 
	On that note, I remember reading about hydraulic lifters in OHV 
engines, and how they can give somewhat the same effect as VTEC, i.e. the 
valves open farther/stay open longer at high RPM for a given camshaft 
grind. Or did I totally misunderstand their usage? If so, why isn't their 
usage more widespread?
	I'm being a bit anal here, but I want to understand this tech 
long before I put an engine and FI system together, (consequently 
spending $$$). If anyone has any papers or books to recommend, I'm 
listening. If they're SAE papers, a source for this info would be 
appreciated, as I don't think I can waltz down to the local library and 
order a treatise on VVT from the reference desk.


		Thanx,
		 Terry