carbed 3.8 to carbed 302 swap Reply #45 – May 03, 2008, 12:15:35 PM Quote from: TurboCoupe50;216977I'm 99% sure they are 18mm, same as the old Ford spark plugs of the 60s(what my Cobra Jet uses)...ok,thats what I thought to,but wanted to double check with someone............thanks again Turbo,for the help. Quote Selected