Getting ready to set valve lash on the 273 on the engine stand. Should I set it right at the .020? Or should I set them tighter or looser since the engine isn't hot?
I'd add about .004. That is NOT because of expansion, but rather, you are just doing a rough first adjustment. I believe the "expansion" actually goes "the other way."
Make sure you use one of the two methods:
Either mark your damper every 90* and use "the chart"
Or use the "EOIC" method which means
Rotate until
EXHAUST just OPENS, and set the intake on that cylinder
Rotate until
INTAKE is almost CLOSED, and set the exhaust on that cylinder