no, 2 14mm will do it but you need one that is somewhat thin.

if the collar on the spring turns with the lock nut you will have to use a pliers or something to hold it while you turn the lock nut.

don't 4 valve jobs that way, checked clearances 100 miles later each time. one or two were off by .01mm by then so i just adjusted them.

once you set the clearances turn the engine over again to check each valve. i usually turn it over 2 times after i have set the clearances.