Ball Cup Effective Length
When working with a ball-and-cup type pushrod from an application like a Ford or Chrysler product with adjustable shaft rockers, it is important to know the “effective” length when ordering custom length pushrods.- In this case, the effective length is the length from the tip of the ball end to the bottom of the seat cup. This is not to be confused by the overall length, which some manufacturers use.- To determine the effective length use your standard adjustable pushrod length checker, the ball-ball style. Set your rocker arm adjusting screw to a mid-adjustment so you have some travel left in both directions. Now, using your length checker, adjust it out until you just come in contact with the ball of the adjusting screw. – This measure from the lifter cup to the tip of the adjusting screw ball is the effective length and the measure most pushrod manufacturers want when ordering custom length ball-cup pushrods. If the overall length were required, you would then add one-half of the diameter of the adjusting screw ball, or the radius of the ball. This plus the effective length will give you an overall length. Conversely, if you know the overall length, you can get the effective length by subtracting the radius of the adjusting ball.

Darrin Anderson
Sterling Bearing Inc
Kansas City, MO
January, 2015