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When building a new engine with new pistons and piston rings it is important that you know how piston ring placement is placed (which I will talk about later). Another thing to remember is having your piston rings correctly gapped. Depending on what your going to use your engine for will determine the gap size you need to achieve. Most piston ring manufacturers recommend a minimum end gap of .004 inches (for stock applications) times the bore diameter for the top piston ring. Example, if you had a 4 inch bore, the end gap would need to be .016 inches. The second compression ring is recommeded to be at .020 inches. Modified engines are a different, because when they produce more horsepower and heat you'll need to compensate for increase thermal expansion. Same as the example I just previous gave using a 4 inch bore the ring gap should be increased to a maximum of .020 inches. The second compression ring for the same modified engine would be recommended to .022 inches (.0055 times the bore diameter). Now onto Nitrous/Blown engines, the top compression ring needs to be opened up even further than both stock or modified engine applications and should be opened up as much as .006 to.007 inches times the bore diameter which would result in an end gap of anywhere between .024 to .028 inches. The second ring for Nitrous or Blown is a gap of .025 to 0.029 inches (again with a 4 inch bore example). The oil rings regardless of engine application are all typically set to a gapping of .015 inches. When doing all this to ensure proper end gapping of piston rings you are assuring a good combustion seal that'll create minimum blowby. Not only will you get a great combustion seal, you'll also allow clearance between the rings and prevent them from rubbing up against each other causing the rings to scuff. The best way to measure ring gap is to place the ring inside the cylinder bore and using a feeler gauge. Becareful to not file at an angle. If the bore has taper wear the end gap will be larger at the top and smaller at the bottom of the bore. It is best to use the bottom position to set ring gap. If you use the top bore, the gap will be too small when the piston reaches the bottom. The ends of the rings may hit each other causing the rings to bind and scuff. Thats why its always best to have a block bored and honed. I hope this helps everyone that attempts to build their engine and the proper gapping they need.

(I'll be doing a write up on proper piston ring placement) :wavey
 

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Rings rotate, crosshatch angle determines the speed at which they will rotate. There are some VERY old odd engines where you will find they tried to pin the rings so they dont rotate, this didnt work out
 

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if the cylinders are that bad and you do not bore and hone, you are wasting your money on file-fit rings anyway.....:nono:
 
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