Here a link to the startup & shutdown procedure of the Allison:
http://rwebs.net/avhistory/opsman/pursuit/section2.htm
And here procedures for the P51, Only the D variant is mentioned so it must be the Packard Merlin variant.
http://rwebs.net/avhistory/opsman/pursuit/section7.htm
However, I'm starting a new topic to try and combine as much official manuals of WW2 aircraft we can find.