[Mgb-v8] [!! SPAM] Re: Ah, the details........

[David Kernberger]

IS this still an unanswered question?  In case it is, I will give it a go.

	By convention a down stroke is when the piston is moving 
towards the crankshaft (ie POWER and intake strokes) and an upstroke 
is when the piston is moving away from the crankshaft (ie compression 
and exhaust strokes).  During the power stroke the force of 
combustion is downward (toward the crank) on the piston but the 
upward resistance offered by the connecting rod and crankshaft is 
partially sideways because the rod is at an angle. The result is the 
piston is jammed against one side of the cylinder more forcefully 
than the other.  That side is the thrust face.

	Therefore, as stated below, the small end of the rod will 
always point toward the thrust face whenever the piston is on a 
downstroke.  But it is only on the power stroke that there is enough 
force for it to matter very much.  On the intake stroke, there is 
essentially no side thrust at all, simply because cylinder pressue is 
relatively low.  In fact the pressure is below atmospheric

I hope that doesn't muddy the waters.

Dave K.



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>Erm, ask yourself how many engines are installed with the crankshaft above the
>combustion chamber!
>   ----- Original Message -----
>   This only leave the question of which way is down?  From which end of the
>cylinder is one looking?
>
>
>   "A simple way to remember which is the thrust face is that the rod points
>   toward the thrust face on the way down the cylinder. Applies to any engine,
>   inline or V" and I'll add "clockwise or anti-clockwise".