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REF: Engine Mechanicals - Sub-01B

Timer Plate Hole Thread Repair

The hole threads are #8-32.

Installing a Helicoil

Using a helicoil repair insert to continue using your factory plate fastener.

  • The existing hole has to be pre-drilled with a #16 bit to accept the helicoil threads (max hole dia. to use this size helicoil is .177“). 1)
  • Tape the drill bit to mark how deep to drill using the helicoil length as a guide. Also take into account the tapered end of the drill bit (it will not be as wide as the main body of the bit on the end which could cause tap and the insert not to fully seat if this dimension is not accounted for).
  • Tap the hole as straight as possible (#16 is the pre-drill size for a #12-24 tap). 2)
  • Insert the helicoil with the insertion tool.
  • Break the installation tab with the tool in the kit or a hole punch.
  • Remove the tab with a small magnet.
Using a Helicoil Kit 3) The proper drill bit is included to enlarge the hole
(to make room for the Helicoil) 4)
Mark the bit with tape as a depth stop
(to keep from drilling too deep) 5)
Carefully tap the hole 6)
Install the helicoil with the insertion tool 7) Break the tab off at the bottom with the punch and
remove it with a small magnet 8)


2)
Starrett tap drill chart
3) , 4) , 5) , 6) , 7) , 8)
Photo by fergerburger of the XLFORUM http://xlforum.net/forums/showthread.php?t=1071324
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