Quote:
Originally Posted by Chilibit
Does an aluminum block expand and contract in response to heat in sync with aluminum heads? Does it make a significant difference?
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It does. If you run a solid lifter engine, with the engine cold, and especially in colder weather, the valve lash will be alot tighter and may make it more difficult or possibly unable to start ( 40-50 F ).
Iron block will not affect valve lash as much, somewhat with aluminum heads, and not alot with iron heads. If you're running hydraulic lifters, then it doesn't matter for starting. However, with an all aluminum engine cold, there may not be alot of pressure on the head gaskets until the engine is warm/hot, and I probably wouldn't run the engine hard until then.