The package says it's not gapped and I don't know what the gap should beIt's a riding MTD lawnmower15.5 hp.
Go to a store like Hobby Lobby and pick up an electric knife for cutting foamThey sell different types of foam, and the goodies to deal with it, plus their people have all kinds of tips and tricks to do it right.
I don't know about pics and clips, but to cut foam circles, you could use an electric can opener to open a can, empty contents and use like a cookie cutter in the foamOtherwise, I have seen people use electric carving knives.
It's quite easy actuallyUsing a utility knife ( the kind with the replacable snap off blades) gently carefully cut the outline of the glass object into the foam rubber or styrofoam, To cut the inside of the outline out, cut at an angle, piece by piece you will be able to carve out the shapeYou could also use two layers of foamCut the shape out of one layer and place on the second layer to form a bottomTo make cutting easier you may want to use the blade without the handleYou can also break the blade off so that it would fit into your cutting area.
I'd set it at between 15 and 18 thouThis is a standard setting for a spark plug in any engineA 25 thou gap is too wideP.S Check that the engine is not flooding with petrol.
