Ok to use spark plugs that are not all the way through the threads in the head???

[billlsbird]

the plugs will run fine, albeit you'll loose a tad of power because of their recessed location. The real problem is that one day you'll try to run in the right plugs, and the threads will be carbon plugged. A plug hole thread chaser will fix it up, but better to avoid it all together.

.....ah ha, yeah it will gum up the threads with carbon! Thanks .... Bill