Proper piston ring gap is a delicate balance.
Too much gap and compression gases and heat will blow by, causing loss of power and torque. Too little gap and the rings can over-expand due to the heat and cause damage to the engine bores or ring lands. In short, ring gap has a direct effect on engine performance and longevity.
Piston ring manufacturers typically include ring gap recommendations for their products. The key is to check the initial ring gap and make any necessary adjustments with piston ring file as necessary.
So what’s the process for checking piston ring gap?
This video covers how to check piston ring gap using a feeler gauge or feeler gauge set, along with a piston ring squaring tool. Keep in mind, ring gap recommendations will vary based on bore size, expected engine pressures, and heat. Things like intended use (street or race) and engine setup (naturally aspirated versus forced induction) will play a part. Do not assume the rings have been pre-gapped or begin the ring gapping process without reading the recommendations from the manufacturer.
To check your ring gaps, you’ll need the following tools: