I have a /6 2.7l with dual Weber ida3c’s. The engine was running great then last week I did two changes on my car. One was that I repositioned my air fuel gauges. I have dual AEM widebands- one for the drivers side bank and one for passenger side. In addition, I had to do some minor wiring work on my alternator which required me to remove my carbs, linkage, shroud, and fan. I did not remove the fuel hoses, I just unbolted the carbs and moved the out of the way. There were no major changes. I put new carb manifold gaskets on when reinstalling. No carb adjustments were made.

Now when driving, the 4,5,6 bank now reading a air fuel ratio of >21 and the other bank reads normal. The car is now sluggish from idle and idles rough. Occasionally when Erving the engine, the a/f ration shots down to 10 for a second. Seems to be running hot and doesn’t start as quickly as normal.

Things that I considered that might have caused the problem.
-plugged idle jets- checked and cleaned- no change
-since I just moved the gauges- some sort of gauge issue. I doubled checked all wiring and all seems fine. Also- why would the engine be sluggish and hard to start if it was just a gauge issue? Doesn’t seem to be the case.
-I check the linkage and there were no changes and everything seems to be functioning the smoothly. No adjustments were made. Could a linkage issue cause a lean issue like this?
-maybe I bumped the distributor when removing the shroud? Why would only one bank be an issue then?
-fuel pressure issue? I have a gauge before the fuel line splits to each carb and it’s running at 3 psi.
-intake leak? I replaced and double checked each intake gasket.

Ideas?

Not an expert, but I would check floats and fuel levels on the bad side. Maybe hung up since moving carb around.

If you took the carbs off and then put them back again, you may have introduced a vacuum leak. Double- and triple-check all the joints in the intake.

--DD

Any chance one of the carb down link adjusters is attached but loose ?.....
loose jamb nuts ?

I’ll check the floats and see if there is movement.

What is a good way to check for a vacuum leak? I don’t see or hear anything unusual.

A loose link is possible however if it was the issue- would it cause a lean issues like this? I had previously visually inspected the links however I did not check to make sure all the nuts were tight. I wonder if I could have bent a linkage piece? At would point I had a hard tine getting the shroud off.