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FE Power Forums => FE Technical Forum => Topic started by: dubsan on June 08, 2013, 10:04:46 PM

Title: Valve adjustment with aluminum heads?
Post by: dubsan on June 08, 2013, 10:04:46 PM

In a new 427 engine stock bore and stroke I have a comp roller cam  under a new set of Edelbrock aluminum heads. Tech sheet from Comp says twenty thou on the valve lash.   Do I need to change this lash to compensate for the different expansion of the alum heads? To my way of thinking the expansion of the head moves the rocker shaft away from the cam. Is this correct? 
Pls advise
thanks
Larry 

Title: Re: Valve adjustment with aluminum heads?
Post by: jayb on June 08, 2013, 11:25:49 PM

That is correct.  Your lash cold will be .006" to .008" tighter than it is when the engine is fully warmed up.  Lash the valves tight to start, warm the engine fully up, and re-set the lash to .020", and you should be good to go.

Title: Re: Valve adjustment with aluminum heads?
Post by: rockhouse66 on June 09, 2013, 06:45:06 PM

I just did this on a 428 with Ed heads and used .014 cold and it came out very close to .020 hot.

Title: Re: Valve adjustment with aluminum heads?
Post by: dubsan on June 10, 2013, 01:45:35 PM

Thank you Jay and Rock
.014 it is  with hot check to follow
Larry