Subaru 12033AB340 Piston Ring Set

When preparing the pistons and new ring sets, make sure they are matched in order to allow checking of their side clearance, end gap measurement and engine assembly. Before putting the rings on it, ensure that the piston ring side clearance is right by inserting some new rings into each groove and employing a feeler gauge to test the spaces between them at various points around every groove. Distinct clearances exist for different rings; compression rings ordinarily have a clearance of about 0.0015 to 0.004 inches. Then, confirm that the ring end gaps fall within specifications by slightly dragging feeler gauges through the ring ends. The standard ring gap (compression ring) is 0.010" - 0.020". Smaller gaps can be adjusted by careful filing of ring ends. Avoid extremely large gaps over 0.040". Subsequently, mount the rings correctly on each piston starting with oil control ring as it has three parts namely spacer/expander, upper side rail and lower side rail which must be carefully inserted into their respective grooves without using a piston ring installation tool.Then make sure that both upper and lower rails can rotate smoothly.Putting number two(middle)ring in place there should be an identification mark pointing up while number one(top)ring should also face upwards with its mark repeating these steps for remaining pistons ensuring accurate installation for each.