90mm piston ring compressor

thingiverse

I use vise grips to squeeze the two tabs together, then tap the outer skin of the ring compressor with a rubber mallet to close any gaps seen between the piston and the compressor, thus ensuring effective sealing. The gap is closed all the way, allowing plenty of clearance for tapping the piston down into the cylinder to handle compressing 90mm pistons like those found in Saab 9-3 engines.