so basically you are making the pushrod seem "shorter" in relation to the distance between the lifter and the rocker (or technically adjuster) so you have more clearance.
I haven't adjusted lash since last winter and my memory was foggy... Getting ready to race soon and it brought the conversation up....
Google aluminum expansion rates, one of my old Crane Cam catalogs says to set the lash .002 loose when setting the valves on a cold cast iron motor, set them .006 tighter cold with aluminum heads on a cast iron block and set them .012 tighter cold on a aluminum block with aluminum heads. I found that information to be accurate on the first all aluminum street Hemi motor I built and on many other mtors since with iron blocks and aluminum heads you do want to check each motor to make sure those settings is what that motor needs and wants 
Quote:
Even though it's a pain at times, I always make a point of checking the lash hot. That's what the engine actually sees, so it makes the most sense. Eliminates the guesswork.
Minor lash variations can make some significant horsepower swings(both ways) on some engines, so it's always a good idea to have this ironed out.
MB
The way I explain it is that since the aluminum expands so much, it's actually pulling the rocker arms away from the block...... 
Quote:I guess you dont like roller cam valve chatter
Yeah I use .006 as the cold/hot difference.. then I
also run my lash .010 tighter than spec calls for
but still with the .006 difference
Quote:Quote:I guess you dont like roller cam valve chatter
Yeah I use .006 as the cold/hot difference.. then I
also run my lash .010 tighter than spec calls for
but still with the .006 difference