I was watching TV while reading the Shop Manual last night. ( I assume that we all do that ) . I heard about the variable valve timing and assumed there was some computer controlled mechanism between the cams and the valves but didn't see anything out of the ordinary.

What am I missing? How can there be a "varible" timing when there isn't anything varible between the crank and the valve?

 

I haven't openned my engine, but variable valve timing is usually contained within the cam gear. So it's not very visible.

It's only on the intake cam of your engine. The 300hp engine has it on both intake and exhaust.

 

variable timing works with oil pressure, that's what I understood.

 

not sure how nissan variable timing work but for VTEC cars theres an extra larger cam lobe for each pair of regular cam lobes. At a specific RPM oil pressure pushes a metal rod across to lock the three cams into place forcing the smaller cam lobes to follow the lift and duration of the larger cam lobe. Easiest way to understand this is to google how vtec works or how does variable valve timing work. Should be easy to find websites with explanations and diagrams.

 

on honda-tech.com there are many vids that explains how the larger cam is engaged to allow greater airflow.

nick (former member of honda-tech and too lazy this morning to link the vid)

 

Vtec and variable valve timing is NOT the same thing.

Variable valve timing I'll change the angle of the cam gear. Changing the exact moment when valves open. They still stay open for the same amount of time.

Vtec activates different cam lobes altogether.

 

There have been a couple of good threads on this....check out the following....one more out there showing a diagram of how oil preassure(load) is used to adjust the timing.....check these for starters.

https://my350z.com/forum/showthread....t=valve+timing

https://my350z.com/forum/showthread....ighlight=CVTCS