Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <DamDeName-at-aol-dot-com> Hi all ---------- I have found the air blast gap to be simple & effective . At Chips web site http.//www.pupman-dot-com under photos/the latest images from list/ sandys air blast gap --------------- try it --- the construction is straight foreward---- Sandy