No it is a brand new 21M that I bought from Novarossi Usa . I also have a brand new .21 T21 5M . The 5M can be turned by hand 360 degrees . It is tight at the top but it can relatively easily be turned . The new 21M is nearly impossible to turn over by hand .
I have a Nova 21M Keep that is brand new . It is so tight you cannot turn it up to and or over TDC by hand . How would you go about measuring head clearance ?
I am looking for info on what other people are running in their Nova 21 Keep M and 21M Keep DD . Nova says C8TGH . But I have seen others mention different . Want to order plugs but don't want to waste money .