Twin Zenith carbs.

Subject: Twin Zenith carbs.
From: Dave_Edmondson@domain.elided
Date: Mon, 12 Aug 96 12:35 CAT

I had a '69 2500 ex factory at Munich which had 2 of these carbs as I
remember. They were indeed very tricky to tune and balance even when new. My
son recently put all the running gear from a '75? 525 into a 518 body and the
engine also had 2 of these carbs. In spite of many hours of work on these
carbs including much help from my local BMW dealer, we were never able to get
them running smoothly or well. I am reluctantly coming to the conclusion
that tuning these comes under the heading of 'black art'!. We ultimately
solved the problem with the single carb manifold from a 3.0 with a Weber - a
38DGAV I think, (it was fitted to the 3 litre UK ford V6 Essex amongst
others). It is a genuine twin choke, both operate in parallel - not
progressive. This works very nicely with good economy, power and smooth idle.
Not the answer you want but the only one we could find. Many people tried to
set up these carbs, they were cleaned and re-jetted but no joy. DaveE.