Not Ranked
John
In addition to the materials the block/head(ford 545a is iron) the biggie is exhaust valve growth----
The cam lobe diameter will have some degrees of area that are designed to take up the movement gently and set it down gently instaed of slamming and dropping---
That differance is then modified by the rocker arm ration to end up with checking lash=
If working on a totally unknown deal--set the lash at .020 cold(won't be too far off either direction) start the engine and bring up to good operating temp--recheck clearance to see how much it moved---if it didn't move too much to indicate trouble--you can probably move the clearance down to area of .014 to .016
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