I believe valve adjustments in general are usually, if not always, done hot.
oldgmctrucks.com is a great resource for ya.
i take mine for a ride before i do them because where i live by the time i get home the engine is good and hot. i have everything ready so when i get home and do it as soon as i shut it down before it has time to cool down.
oldgmctrucks has a easy tried and true method.
