A large problem with 3.1 builds is someone is always looking for a way to build the thing cheaper and using junkyard parts. I can not agree more with the before mentioning of balancing. Balance the entire assembly. From the front pulley all the way tru to the flywheel. Since all the pieces are out anyway, it makes too m,uch sense. After lots of looking around and reading forums I decided to build mine the way it has been done in Japan for years. Why go this route? Well if they have strokers that run with big carbs and blow-thru turbo charging on drag cars that pull double duty as daily drivers than they have some how solved the reliability factor. Builders recommend either the F54 or N42 block. This debate could go forever. Just pick one already. Ld crank is a must. Take everything you know about different rod/piston combinations and forget it. Manufactures such as HKS, Tomei,Kameari and others have been making special pistons with redesigned ring specs to fit various rods lenghts. Get this they even tell you which set of connecting rods to use. They also tell you what the displacement will be using the LD crank and what piston set you purchase. For example my LD crank, 89mm tomei pistons and L20 (inline 6) connecting rods clears the 3.1 liter build safely and will hold thru future plans of turbo. Morale of the story is if you are going to do it, do it correctly don't wing it with junkyard parts trying to wing it.