Lister D tappet gap

Hi All,
Can anyone kindly tell me the correct tappet gap for a Lister D- I am confused as there is a guy on You Tube who does a good video on decarbonising a Lister D and he says to set the tappets at 15thou', the restoration book says the gap should be 30thou' - and there is another guy on You Tube who says that the original Lister manual says 5-10thou'!Help!Thanks.
Kev.

Set them to 5-10 thou, the 30 thou was a misprint in the reprinted Lister book and has since been apologised for and corrected. A retired Lister engineer told me that they just set them by feel, as long as there was a clearance that was good enough as they don't exactly get hot enough to tighten up in use.

Pete.

Hi Pete.
Thanks for your reply - that certainly clarifies matters and makes a lot of sense.
Kev.