[6pack] Timing (is everything))

[Crouter, Bruce CIC]

I hope you are all enjoying the weekend, I have a confusing situation that I
thought someone smarter than me might be able to help me with.

I have a very loyal 75 TR6.  The vacuum system was cut up many years ago by
the PO.  It has a retard unit that I hooked up to a port under the intake
manifold that provides high vacuum at low rpm.  When I set the timing the big
blue book tells me to set it at 4 ATDC with the retard unit disconnected.
When I hook the retard unit back up the timing retards to something around 12
ATDC and the car (as you would expect) runs terribly until high RPMs are
reached.  To compensate I set the timing at 10 BTDC with the retard unit
connected and all seems right.  Do I have the retard unit hooked up to the
wrong vacuum port or is there some real obvious thing I am missing here.  Not
a serious problem, I just thought someone may have some insight.  Thanks in
advance.

Bruce Crouter
Regina, Saskatchewan, Canada