Re: Correct spark plugs for 87 225 Looper
Unless the recommended s/plug has been superseded up to the Champion QL78TC plugs and I'm not aware of the update..........
The original recommended spark plug is the Champion QL77JC4 plug, gapped at either the original recommended gap of .040 or the later recommended gap (late 1990's) of .030 . One gap or the other may provide improved performance at either idle or the higher rpms.... it varies from engine to engine for some reason.