CAT 3306 injectior question (D5B)

I've been rebuilding the fuel system on a D5B with a 3306 engine. The factory service manual indicates that the
collar which holds the injector valve in the pre-combustion chamber should be tightened to 10 lb/ft. Is this
really the correct value? It seems ridiculously low for a 1" nut that holds the injector against the full pressure of combustion. Breaking these nuts free required a 1/2 breaker bar with an extension, indicating that they
were tightened to a much higher value than 10...

CAT 3306 injectior question (D5B)

CAT 3306 injectior question (D5B)