Thanks for all replies.

Shortwave Sportfishing: I did not even know the term "one lung flywheel
engine" now I have something to Google.

Eisboch: FMV was the biggest employer in the region. The word
"outsorcing" was not invented then so they manufactured everything in
the ship. Big engines, ship furniture, everything. They apparently had
a small engine workshop too.

basskisser: I am not familiar with the terms but the engine fires at
every revolution.

Best
Kamil