How to rotate your motor

Need to check your valve clearances?  Need to adjust your points or set static timing?  You need to rotate your motor!

Some people advocate using a remote starter to 'bump' the motor around to the correct point in the 4 stroke cycle.  This approach works, but it's inexact and particularly for checking valve clearances it's easier to keep track of incremental rotations.

Here's what you need

  • A 1/2 in. ratchet
  • A socket that fits on the locknut on your alternator or generator, as applicable
  • A socket extension that will allow the arc of the ractchet handle (and your knuckles) to avoid imprtant bits on the back of your motor


  1. Disconnect your battery ground cable.  Do it now, stumpy.
  2. Pop the cap on your distributor.  This will let you see how far you've rotated, and you'll need to do it to set points or static timing anyway.
  3. Set your ratchet to go clockwise,  put the socket on the extension, the extension on the nut, and then the ratchet on the extension.
  4. Give the ratchet a hank to move the motor clockwise.  If the belt slips, tighten the belt and repeat as neccessary.  This is also a great way to check if your pulleys are clean and belt tension good.
  5. Belt tension good?  Rotate the motor incrementally and keep track of small changes on the timing scale and the big picture by watching your distributor rotor.  The distributor gear has a 1:4 mechanical advantage.
  6. Repeat.  When you're done, replace the distributor cap and battery ground cable.