Installing piston rings

Installing piston rings: How to set the ring gap correctly

You not only have to check the ring gap of your piston rings, but also adjust it. You do this individually for each cylinder. Remember to note the measured values in your log. There you can enter, among other things, the bore and the ring gap. This way you always have the values ready when you want to make further changes. Your pistons always come with installation instructions, the “ring installation guidelines”. Follow these steps to set the ring gap:

1. Sort the pistons and the associated piston rings in the correct order. This results in the fewest errors.
2. Observe the installation direction: on the intake side, the pockets in the piston are deeper.
3. The first piston ring is shiny, the second is darker and matte. The marking on the ring faces upwards.
4. Then press the ring you want to work on into the cylinder. We use a self-made plastic tool for this, but you can also use the piston. Make sure that the piston ring is really parallel to the opening.
5. Next you need feeler gauges (gap gauges) to measure the ring gap. Which ring gap you need depends on your engine, your requirements, etc.
6. If the feeler gauge does not fit into the gap, you have to grind the piston ring. Work on only one side to achieve an optimal result. Approach it slowly and do not grind off too much at once.
7. Remove the dirt from the piston ring and check whether the ends are straight.
8. Check again with the feeler gauge and adjust the piston ring until you have reached the desired value.
9. Then deburr all sides so as not to score the cylinder.
10. For installation on the piston, fix it first.
11. Then check whether the piston ring can rotate in the piston or whether it sticks. If that is the case, it must be deburred again.
12. If everything is fine, spread the ring apart starting from the ends so that you can slip it over the piston (without scratching it).
13. Check again how easily it rotates.
14. Once you have installed all the rings, turn them so that the gaps do not lie on top of each other (like a Mercedes star).
15. When the piston is finished, you can install it. We use a Teflon sleeve for this. You can also use a clamping band, but we recommend the funnel.
16. Supply the sleeve, the piston, the piston rings and the conrod bearings with plenty of oil.
17. Then carefully place the sleeve over the piston with fingertip feel to pre-tension the rings.
18. Once the cylinder is oiled, you can insert the pistons in the installation direction. Check again whether everything is correctly aligned. The sleeve must rest on the block. Finally, carefully press the piston into the cylinder.