Hyundai Assembly 4 - Balancing Rods

I edited this video to its finished state, and RojoDelChocolate handed me a track with no collaboration that was the right length and rhythm. I literally did nothing to the video once the audio track was dropped in, and that's just how it went. I can't believe it. It's like when you're pumping gas into a Ford F150 full-blast and release the pump handle to stop right on $80.00 even. He's got more musical talent in his pinky fingernail than I have mechanical ability in my spleen, appendix and tonsils combined. Thank you RojoDelChocolate. Here I'm cleaning up the fly cuts, balancing the piston and rod assemblies and preparing to double-check my valve clearance. I had to start by cleaning up and re-lubricating every part that was removed to prevent contamination of the assembly. This is the tedious part of doing the job right. We learned that this whole engine assembly was pretty far-gone in previous videos, way past its service limits, so making it fit and work again takes extensive testing, machining, and re-testing to ensure all of the parts fit. This is likely the most challenging build I will perform on any car in my driveway. It has been so far. But because I have not demonstrated the basics of engine balancing beyond what a machine shop has to do to zero balance a flat-plane crankshaft, I thought I'd give it its own video right here with one of the test assemblies. When you balance rods by themselves, you balance the big-end and the pin-bore separately. You get weights of both ends of the rod using a jig and a process that I don't demonstrate in this video. The reason you do this is because the position of the weight behaves differently relative to its distance from the crankshaft pin. Weight on the big end has a greater effect than if there's extra weight on the pin bore, but they both matter as do their combined weights. The best balanced engines have every part of the piston and rod assemblies balanced separately within .1 grams using the method I just described, and not the method shown in this video. The method shown here involves weighing ALL of the piston and rod assembly components together, and then taking out the difference just on the casting lines of the connecting rod. They were already off-balance and had never been balanced before. This is an improvement, not perfection. It's still something this engine needed to have done. I'm not using the big-end/small-end method here because these pistons are pressed-on and if I try to remove them from the rod, it will shatter the piston skirts. No thank you. I'm not replacing these pistons. The reason I grind down the casting lines is because it's weight is in a neutral territory, extending from the big end to the small end. It's easier to take an even amount off when you grind across the entire length of the rods. This method leaves a lot up to assumption as there's no way to determine which end of the rod is heavier, or if the weight is in a wrist pin or piston. All this does is ensure the crankshaft is spinning an even amount of weight on all 4 of its rod journals. Grams of weight turn into pounds of force at idle speeds. My goal is to remove that vibration at any and all rotations per minute if I can. So I make them all the same within 1.0 grams of their combined weight. If you're assembling and balancing all NEW parts, not parts that have worn together and need to go back in the same holes... you will have to balance the individual parts and pieces. This is the poor man's method. Even with the new parts you still do the poor man's method once you're done balancing the individual parts and assemble them, but sometimes when you're lucky with the new parts, you can just swap around the rods, pins and fasteners to balance the weights on each assembly and not have to grind anything at all. That's awfully nice when that happens. You know the Hyundai won't let me get away with that. Removing stress risers might help strengthen the rods, but it's not what I'm after here or else I would have removed the whole casting line from all of them. These rods should be fine for my goals. My goal is to remove just enough from all of the fatter rods (weight wise) to match the lightest one. Balancing an inline 4 engine with a flat-plane crank is easy if you have already balanced the crankshaft. This crank was already balanced for the GSX motor on a previous occasion. It's zero'd out. In order to balance the rotating assembly, all you do is make the piston and rod assemblies weigh identically to its neighbors. Just 3 grams of weight can produce over a hundred pounds of lateral forces at red-line so this is an aspect of engine building that you should not overlook. All you need to do is get all of them within 1 gram. The scale I'm using measures whole grams, so that's all I can do anyway. This method is acceptable for balancing a rotating assembly as long as you're smart about how to remove the weight.