old rule of thumb is that you will gain .001'' gap every thousand miles due to erosion of the electrodes...so unless you re-gap every couple thou miles, no sense worrying 'bout 'tit.
for reduced emissions at idle, a wider gap (up to .060'') will help....under load, the tighter gap produces fewer misfires and more power.
i gap sbc plugs using the ''go-no go'' method --an .035'' wire gauge will ''go'' thru the gap, and an .040'' wire will not.
be careful that you do NOT damage the porcelain center insulator when adjusting the gap.
