Perkins Cylinder Liners useful information
Unfinished Liner (Also know as 'semi-finished' liner)
This type of liner has a finished exterior but the inner bore will require boring and honing to the correct finished size after it has been pressed into the parent bore of the block.
Finished Liner ( Also know as pre-finished)
As the name implies this liner is fully finished both internally and externally and once installed it will be ready to accept the piston without any further machining. It is the most popular liner type as costs and work are reduced. When possible we will supply this type of liner with our engine overhaul kits.
See photo above. Parallel Liners are held in place via an interference fit between the liner and the parent bore in the block. This means they will need to pressed hard into the parent bore. All parallel liners are semi-finished and special care should be taken when installing as they can crack if not aligned correctly or fitted with incorrect tools.
Flanged Liner (also known as 'slip fit' liner)
Again as shown in the above photo these liners have a lip or flange on the top edge of the liner. The flange locates into a counter bore cut at the top of the parent bore. Flanged liners can be either fully finished or semi-finished internally.