Achieve maximum performance with high piston ring placement and low thermal conductivity. Top rings operate at higher temps and require slightly larger end gaps (4. 000" bore x . 0065" gap factor = . 026" total end gap). It is recommended that ignition timing be retarded 2-4 degrees. Sold in sets of eight with wrist pins. Coated skirts. Designated as O. E. relacement for engines manufactured in years Truck 69-78, Passenger Car 69-70, Corvette 90-91. All other years not legal for sale or use on pollution controlled vehicles. Actual compression height of this piston is 1. 561 plus . 004. This number replaces 3418H. Modern piston design locates the top ring higher for improved performance. a high top ring operates at higher temperatures and requires a larger top ring end gap. To find the proper ring end gap, multiply your bore size by the ring end gap factor listed on the chart (i. e. , Street Normally Aspirated 4. 000" bore x . 0065" gap factor = . 026" total top ring end gap). Your Hypereutectic Claimer race piston will expand less than typical cast or forged pistons. Because of this and the wear characteristics of the hypereutectic alloy, you can run tight piston-to-wall clearances. NOTE: Claimer piston engines will require 2-4 degrees less total ignition timing. One key to top performance is to have all cylinders longing for the same timing numbers. Equal air flow, fuel mix, quench, chamber temperature, swirl, and compression at each cylinder work to this end.Pit Stop USA offers KB Pistons Performance Claimer Performance Series SB Chevy Flat Top Piston Set - 4.155" Bore - 3.750" Stroke - 5.565" Rod Length 9907HC.030 at low everyday prices. Be sure to check out all of our products from KB Performance Pistons including KB Performance Pistons Hypereutectic Pistons - SB Chevy.