I guess if you have never heard about heating the cylinder head, you have never been around a Tight True ABC engine. A little heat with a heat gun on the Head is done all the time with tight Car, Boat, and Airplane engines for the first start up. OS's if these are the engines you are used to are not ABC engines and do not have there cylinder to piston fits any where near as tight. All the pre heating does is loosen the fit slightly so you can start it with out it sticking at top dead center, and dramaticaly reduces the stress on the crankshaft and connecting rod on the first start up.