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To anyone who has rebuilt their N14 engine with aftermarket pistons and rods: Did the engine require re-balancing to accommodate the change in weight of the pistons and rods (I've installed CP pistons and rods)? This without regrinding the crank. And making the broad assumption that the Pistons and rods came balanced which I think they do. At least they are the same weight.
Please discuss. Thanks, Dan
A small scale is invaluable in these situations. You could have or should have weighed all parts (rings, bearings, pistons, pins, bolts and rods) and assembled them by weight to get them as close to balanced as possible. If they are balanced corretly no other balancing should be required.
The CP set has pretty close weight tolerances, and should be OK as is. Since I retired from the QA / QC world of mfg'g, have an old balance scale and lotsa time, I balanced my sets to within a few milli grams of each other. The wife wasn't too happy during the process, but at least the parts were clean and odor-free. CP stuff was put together as four complete sets, dry with no lube, then weighed and trimmed as req'd --- trimmed in the garage, not the dining room. I used a Dremel grinding stone inside the piston where there's the most excess material. Didn't remove any from the rods. Ideally, each part would have been weighed and trimmed, then put together and balanced again as a set. Also took the crank to a shop for it to be re-balanced. The guy told me that the technique for our in-line 4-cyl crank is similar to a static balance on tires --- no spinning. I wasn't able to watch the process, but when it came back, I noticed a small hole had been drilled in one of the counter-weights --- maybe because I didn't have the flywheel guide pin installed? Not sure whether or not it should have been included --- which gets the guide pin for factory balance, the crank or flywheel? Something to consider if you do balancing. Don't forget to thoroughly rinse the piston assemblies before installing in the engine.
Was all this required? Probably not, but I'm targeting over 360WHP and want to minimize stress wherever I can. Now, if I can ever get this thing put back together, without screwing something up ---
12-08-2018, 06:07 PM
