i have merlin 310 014C heads on my 468.
have had many spark plug issues,mostly installation and fouling problems.
the area around the plug is not larger than the plug so you have to use a real thin wall socket,you do not much to grab on the hex area.
have used champion c61,autolite ar2593,ngk 9.
spoke to bill mitchell at world and he said to try a ngk 7496.
thay came in today and i find they are project tip.
will they work?
do not have piston info

thanks in advance

im running ngk yr5 plugs in my 468.............theyre a non projected plug as the ngk tech i spoke with said that with the aluminum dome pistons im running theyr not a good idea???????? the yr5 plugs run alot better than the old delcos!! had to one up my jetting though. id go with a non projected plug to be safe until you know otherwise. it would be a bummer to be taken out by a spark plug issue.