Center the piston cap on your Corken 891 Compressor in 3 simple steps.
With the piston cap set screws loose, use 2 15/1000th feeler gauges to shim between the piston cap and Cylinder wall on two sides of the piston cap.
Next, Center the piston cap inside the Cylinder wall. Make sure to leave an even clearance around the entire Piston cap to ensure proper operation.
Next use a T handle or ratchet to tighten the four set screws on the Piston cap. This will lock the piston cap into place allowing you to remove the feeler gauges.