QUOTE(SLITS @ Sep 3 2010, 07:40 PM)
'73 has two pipes on the throttle body for vacuum lines ... '74 has one. Porsche determined the advance was not needed and only used the retard function.
thats interesting (or just retarded), i remember in the early 80's ca. smog testing, you had to disconect & plug the dist. advance, along with a nox decal put on the speedo. (on my 442 & mustang anyway). the reason was to lower combustion temps. under 2500* to eliminate the NOX emissions. what it really did was lower m.p.g. & power.
sorry for the hijack
side note: 73 up had the side shift, some early 73's had the lighter, non reinforced doors.