Michael,
Your car is now working the way mine does give or take a few psi of control pressure and system pressure. There is a method for adjusting system pressure that involves adding or removing shims within the fuel distributor. I haven't done this, but it looks straight forward. I'll send you the procedure. I'll also send you the control presure graph for a 78-79 US 911SC.
Here's my understanding of how the two vacuum lines work.
The two vacuum lines are connected on either side of the throttle plate. The lower connection to the WUR comes from the intake side of the throttle plate. There is a vacuum on this line at idle. The other line comes from the other side of the throttle plate. At idle, there is very little vacuum on this line. This vacuum differential cause the WUR control pressure to go up (it leans the mixture at idle). When the throttle is wide open, the vacuum differential is small and the WUR control pressure decreases (this is full throttle enrichment). The thermovalve is used at cold start to shut off the vacuum on the lower line which causes the WUR to decrease control pressure and richen the mixture.
------------------
Bill Krause
'79 911SC Euro
|