<VV> adjusting valves - I want to believe!

[Bryan Blackwell]

Hi folks,

I finally had time to read Craig's excellent analysis.  It had  
occurred to me as well that part of the 1/4 turn vs. 1 turn  
adjustment could be whether the valves were adjusted hot and running  
or not (this doesn't include performance engines where we are trying  
to avoid pump up).  I'll add a data point.  You may recall I just  
completed a piston and barrel swap on the basement 110 that went into  
the '66.  On that engine I adjusted the valves cold and tightened  
them to 1/2 turn.  As suggested by Craig's numbers, the engine runs  
fine, but in fact one valve always has a little "tick" to it.  I have  
to do a couple other things to it, so I'll adjust the valves to 3/4  
turn and see how that works.  One thing not calculated previously is  
that although the engine grows, so do the valves, which may explain  
why the calculated valve adjustment doesn't quite match what we see  
in practice.

--Bryan

On Nov 3, 2008, at 12:23 AM, Craig Nicol wrote:

> So the questions are: Why does 1/4 turn seem to work so well?
>
> If the preload is set to 1/4 turn when cold, according to this  
> analysis it
> should clatter when hot. Perhaps 1/4 turn works only if adjusted at
> operating temperature. I wonder if this unspoken need to have the  
> engine at
> temperature is why we hear so much cold/hot, 1/4 turn-1/2 turn-1-turn
> controversy?  Maybe 1-turn is the right answer if valves are  
> adjusted cold
> and 1/2-1/4 turn is the answer if adjusted hot.
> Craig Nicol