[TR] TR3 Timing Chain Cover

[terryrs at comcast.net]

First, total hats off to Moss.  They have a series of videos about setting timing on cars with no cam or crank gear marks.  Easy peasy.  Thank you to them.

Now, the timing chain cover has a bolt hole just above the crank hole.  The bolt may not have been on the engine when I disassembled it, since I'm pretty fastidious about bagging and tagging, but...whatever.  

The bolt doesn't show in exploded diagrams of the engine.  Anybody know what it is?

Terry Smith, '59 TR3A
New Hampshire