HYD Roller Lifter Problems - Powell Machine You Tube.

[Barry_R]

Note - Hot vs cold lash on this iron/iron 351C is the same.

That's the way it is on FE's too.  I've never seen lash change between cold/hot on an iron/iron combo.

I have.  But it's not a lot.  Maybe .003-.004 max.

[Rory428]

With iron block and heads, I have seen next to no change in valve lash, when using stock type iron adjustable rocker arms, but with aluminum roller rockers, I have seen a difference of .002".