Engine Building Fundamentals: Ring Compressor
- One of the easiest times to damage a new set of piston rings is when the piston is being installed into the bore.
In order to do this, the rings need to be compressed into the ring grooves on the piston, and this is achieved with a ring compressor.
Ring compressors come in a few varieties, but the most common being a low-cost style of ratchet ring compressor where a middle sleeve is placed over the piston, and tightened up against the skid of the piston to compress the rings.
The piston is then placed in the bore, and gently tapped into place.
When used with care, this style of ring compressor can achieve excellent results.
However, it's also possible to have a ring pop out during the installation process which can quickly destroy the ring, as well as potentially damaging the bore as well.
My own preference is to use a tapered-style ring compressor where the entire piston is pushed through a machine sleeve with an internal taper that compresses the rings as the piston moves through the compressor.
The down side is that this style of compressor will only work for a specific bore size.
So you need a ring compressor to suit each size of bore that you expect to work with.
This can understandably get expensive unless you only ever plan on working with one or two bore sizes.
However, it only takes one damaged or broken piston ring to make you wish you'd gone down this route.