[Vwdiesel] Cracked Heads...block heads

[Mark Shepherd]

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Take a block of  alumin(i)um  drill a big hole in it...heat it up...it gets
bigger... ie longer wider deeper.... but does the hole get bigger or smaller?

Take a  high carbon steel ring heat in same bonfire does it get bigger or
smaller?

Try some steel with 35% nickel... 'Invar' ...apparently it doesnt move much
either way!

I feel that these cracks are in the weak area that gets torn apart by a
combination of hole shrinking and ring expanding...perhaps someone could  heat
up a head in a kiln without an insert and also heat up an insert without a
head and take a couple of measurements to end the dispute ...What definitely
doesnt happen is ring shrinks and hole gets bigger!



Mark(the Miser)UK "If I can bend it or stick it together,I will!"

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===References:===
  1. http://g.msn.com/8HMZENUK/2740