Hi navpro,

If you do asearch on this site you will turn up quite a few; www.wackerengines.com - www.carrprecision.com - www.rcignitions.com - http://bennettbuilt.com/ - and others I'm sure I haven't listed them all. The concensus seems to be at least 12-15 inches from engine and electronic igniton if equipped and if CG allows. Good luck! Ben