Spark plugs

[gnj37]

Plugs have fouled up on 13b fitted are ngk r  br8et Times 1 denso W 22 ebr times 3!!!!!!!!! The engine is i think a us 13b import and the problem is that there are little square notches around plug holes so the plugs that i have cant be tightened properly Any body have any ideas as these spark plugs would need to have a very small spanner fitting  i have also gotten rid of rats nest and running on ida Webber if this makes any difference cheers.