http://blog.wiseco.com/everything-you-need-to-know-about-ring-gap
The process begins with inserting the ring into the bore, and making sure it is square using a squaring tool to align it properly. A feeler gauge inserted into the ring gap will show you the existing dimension, and from there you can make your adjustments. For a street engine, multiplying your bore size by 0.004in will give you the top ring gap you are looking for.
- 004 x 4.00in bore = 0.016 inch ring gap
For high performance engines, the multiplier changes to add more clearance, but the math stays the same:
- Modified or Nitrous Oxide - 0.005in x 4.00in bore = 0.020 inch ring gap
- High Performance Racing - .0055in x 4.00in bore = 0.022 inch ring gap
- Racing with Nitrous/Turbo - 0.006in x 4.00in bore = 0.024 inch ring gap
- Racing Blower/Supercharger - 0.007 x 4.00in bore = 0.028 inch ring gap
For the second ring, the process is the same, but with a slightly different gap, based on application:
- Street - 0.005in x bore size
- Modified or Nitrous Oxide - 0.0055in x bore size
- High Performance Racing - 0.0053in x bore size
- Racing with Nitrous/Turbo - 0.0057in x bore size
- Racing Blower/Supercharger - 0.0063in x bore size