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Engine Assembly Tips, Part Two: Pistons and Rings By Tyler Gerrick, WyoTech-Daytona Motorcycle Instructor


Like everything else inside the engine, pistons require special attention and care. Most of us don’t have the re- quired equipment to bore/hone cylinders to size, so this job is often sent out to a reputable machine shop. Many machine shops do mostly automotive work, so make sure they have the appropriate torque plates. The use of torque plates during the boring/honing process is very important because they simulate the clamp load of the assembled top end. The piston-to-cylinder wall clearance is quite small and it is crucial to the engine operation that it is correct. Don’t assume that it is correct - measure it!


Next, check the ring end gap. Put each ring (one at a time) into the clean cylinder bore about an inch down from the head gasket surface. The ring needs to be completely straight in the bore. I use a piston to “square” it up in the bore. Use feeler gauges to determine the end gap. If the end gap for the compression and scraper (the top two) rings is too small, you can file the ends of the rings to obtain the correct clearance. I recommend using an actual piston ring filer tool or some small jeweler’s files. Make sure to lightly “debur” the filed edges so they don’t scratch the cylinder bore. Most manufac- tures do not recommend filing oil control rings (the bottom rings). All the parts need to be thoroughly cleaned and lightly oiled for assembly. It is important to use a piston ring compressor to compress the rings enough to get the piston into the cylinder. Most piston ring compressors are tapered at the bottom for automotive use and should be used upside down when installing the piston from the bottom of the cylinder. Because of the many differences in metallurgy, design, and application, there is not a “one spec applies to all” when it comes to pistons and rings. All of the critical specifications are subject to change, so you should check the service manual or instructions every time.


Do it right - Do it once!


Modifying your vehicle while obeying the law! By Cliff Peerson, WyoTech-Sacramento


Most of us wish to work on our vehicle, make the desired modifications and not concern ourselves with legal issues or breaking the law. Since the early 1970s, California has been heavily emissions regulated and many other states are following their lead by adding state emission inspection programs. So how do you know that you’re conducting legal modifications to your hot rod or daily driver?


First, many enthusiasts believe that “having your cake and eating it too” is not possible when discussing emission- legal modifications. That is simply not the case! There are many legal upgrades and performance enhancements that can be done while complying with the law. One just needs to pay attention to the parts they are purchasing and ensure they meet the necessary guidelines. This is not as complicated or difficult as it sounds!


Since California has taken lead with emissions regulations, they have also created a great website to inform us of what is legal concerning vehicle modifications. Visit California Air Resources Board website at www.arb.ca.gov to find which aftermarket parts are 50-state emissions legal. What you can do legally will amaze you! The menu on the left side of the screen, second down from the top, shows aftermarket parts. When you click on that you can simply look up part numbers or manufacturers to find the legal parts for your vehicle.


VISIT US ONLINE AT WWW.FLHRH.COM I FLORIDA HOT RODS & HOGS I JUNE 2012 29


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