It is a reference to engine timing.  BTDC = Before Top Dead Center. TDC is
when piston #1 is at it's highest level on the compression stroke.  6deg
BTDC means that the plug will fire when the piston is 6 degrees (according
to the crank) before reaching TDC.

At 14:27 5/21/98 -0400, Edward Berlett wrote:
>Ok.  What does BTDT mean?
>
>
>Thanks
>
>Ed
>
>

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