Welcome to the forum Steve. You've come to the right place to start the search for information for your Uncle.
I also worked in the engine room of the QE2 but didn't join Cunard until 1984, so I never knew your Uncle. However, there would have been crew that both he and I would have known, as some of the 'old hands' had also worked on the original QM & QE. There might be some forum members who remember your Uncle. There may be others who are not yet members of the forum who visit the website who might be interested in joining if they see your Uncle mentioned, so keep checking back.
Do you know what position he had on the ship? There were Asst Mechanics, Mechanics, Electricians and other trades in the Technical Department? Perhaps he was an officer?
Take a look at
https://www.theqe2story.com/forum/index.php/topic,1032.0.htmlYou should find some interesting posts and photos relating to the engine room there. I'm pretty sure your Uncle would recognise the engine room photos.
Also
https://www.theqe2story.com/forum/index.php/topic,971.0.html relates to the last steam crossing of the Atlantic by the ship, which you might find interesting.
The ship was steam driven until 1986, when she went for a 6 month refit in Germany for it's Diesel/Electric conversion.