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[Varooom]

I like to put a dab of anti seize goo on my plug threads after making sure they're clean and the hole is too.  Good to blow the hole out BEFORE removing the plug to keep any pebbles from getting into the combustion chamber.  The goo helps the plug go in smoothly with finger pressure only and insures it'll come out without problems.
Varooom

[chief]

Its easy to cross thread... so they may be screwed up. Ensure you are using the correct plug as well.

[bart1966]

Has anyone had problems with the threads for spark plugs??? I am not sure if the guy before me messed them up but the are ugly!! Had one of my spark plugs just blow out driving down the road.