Need to rebuild a briggs 14 hp I/C Quiet Engine Model-287707 Type-022002 Code-9309084A The Engine was run dry on oil but now it runs fine at high trottle but at low trottle it puffs white smoke and backfires every now and then should I put new rings in it or is it the head gasket and if it is does anyone have a step by step rebuild manual all help would be Greatly needed and Appre..! Thanks