CAM timing diagram in Wayne's book

[hobieboy]

Hi,
Just re-reading Wayne's engine book & BA's performance handbook. Both had a SC Timing diagram to illustrate relationship between crankshaft rotation & valve lifts.

But... the dotted line leading to the TDC overlap point says valve lifts is 0.1mm/0.0039" for the SC cam. But - Wayne's book said that the SC cam spec should be 1mm at this point.

So - is this a typo or am I missing something?

thanks...

[Wayne 962]

Hmm, the diagram is indeed confusing. In addition, there is a typo in Bruce's book which makes it more difficult to understand.

The .1mm is valve lift with a .1mm clearance on the valves (from the valve adjustment). The right caption should indicate the value with the valve clearance, not the actual value. In reality, to be clearer, it should say 1mm. Not really a typo necessarily, but very unclear. I'll add this to the correction list...

-Wayne

[hobieboy]

Thanks for the clarification Wayne

That's what I thought - at TDC overlap, with .1mm clearance on the valves, the lift should be 1mm in this case.

I think it would be ok to simply change the value indicated by the dotted line to be 1mm as the text always highlight the .1mm clearance part.