Well, the solution has finally presented itself, but I'm not a bit confused about something else.

After multiple suggests from quite a few people, B20Paul suggested that I removed the vacuum hose to my booster to check for a leak.

So while idling, I removed the vacuum hose from the intake and the car immediately started to die. However, I quickly slapped a vacuum cap over the fitting and suddenly the car recovered and began to run very well. This was quite a shock. Both carbs could be balanced while I was able to adjust my idle down to a smooth 900 rpms.

Assuming that the fault lay somewhere in the 3-way vacuum between the intake, flame trap and booster, I went and picked up a nice brass three-way fitting and new clean 9.5mm vacuum hose and compression clamps. After some fiddling around and testing some configurations with my vacuum check valve (from the 1800E), I realized that there was *NO* vacuum leak at the brake booster. A straight connection from the intake to the booster gave me very good idle and engine behavior.

The problem is at the flame trap. If I put a connection to the flame trap into the vacuum circuit to the intake, I get *very* poor engine behavior. If the trap is left out, or otherwise plugged (by a reversed vacuum check valve) all is well.

However, I *know* that the system is not supposed to function this way.
I'm now worried about excess crankcase pressure and blowing my new main seals out (which happened to a 740 I used to have). I could install the U-shaped "road pipe" I have from an earlier B18, but I really shouldn't have to. Something is not right here. The flame trap already has a new O ring seal at the block. So maybe the problem is the B20-style flame trap versus the B18 style trap?

And my usual question... Any Thoughts or Suggestions??