Selecting the correct replacement piston for your Perkins can be a problem. This Foley Tech Tip, one of an ongoing series to help engine rebuilders, discusses Perkins pistons and gives a guide to their selection.

Piston Design

The pistons vary in the number of rings used, design of the top (flat, dished, dished with a protrusion), expansion characteristics, size, and piston pin diameter. Perkins over the years has tended to decrease the number of rings used, sometimes even leaving some grooves empty.

To aid in flame propagation, Perkins has tended to put a protrusion in the center of their dish top pistons. We feel that the non-protrusion equipped pistons have their advantages for reasons of balance, locus of mass, weight and simplicity (the protrusion may carbon-up). Some pistons, especially in reefer aplications, have controlled expansion characteristics with specific rings.

Additionally, 4108 oversize pistons are available for those who do not want to change liners. Finally, piston pin dimensions and con rods vary from turbo to non-turbo engines. See Foley Tech Tip #3 for some tips on reconditioning these rods.

Choosing the Correct Piston

The easiest way to ensure you are getting the right piston is to call us with your serial number. See Foley Tech Tip #10 for a field guide diagram regarding what these numbers look like and where they are located on your engine. With our 80 years of experience, we can ensure that you get the right piston the first time.

Please call, fax or email us with any questions.