Having trouble with my 4 Zenith Stromberg carbs.
 

Hello Jaguar Forum. We just rebuilt all 4 Strombergs on our 71 E type. It's not running right. It idles great. When we start driving, there is no power until I pull the choke cable out, then it blasts down the street. At idle, I can lift the passenger side pistons on both carbs and the car keeps idling. On the drivers side, if I barely lift either piston the car stumbles and dies. Please give me a place to start.

GSA look at the WSM and follow the steps to correctly set the linkage. check the fuel return valve as well as the fuel feed to the lean side. I would not drive until I sorted this--you are obviously very lean on the drivers side. Good luck

As usual, George has some good advice. I would add checking for vacuum leaks using a spray can of starter fluid. The Strombergs are set so lean, it does not take a huge leak to upset them. At least that was my experience with them on a 4.2. Finally converted to triple SUs and have been smiling ever since. Good luck.

Ah you have a V12 car, consider looking at the fuel injection upgrade (that engine was designed for fuel injection and just getting those carbs properly balanced is a nightmare). This actually sounds like your carbs aren't properly balanced/jetted. There is another thread that talks to fuel injection. But if it runs with the choke out it may be one or more carbs is jetted to lean, possible linkage, or not properly balanced. I balanced a v12 once PITA. If I had a V12 first thing, and I mean the very first thing, I'd do is get rid of those damn 4 Strombergs.

I'm a little late to the discussion but am wondering how things worked out. I have a 1971 Series 3 2+2 FHC and have been fooling around with the carbs. Assuming your ignition is functioning correctly and the timing is correct, I'd first check for vacuum leaks, which is easy. Your lifting of the carb cylinders with stumbling and dieing indicates that the mixture is too lean. Get a carb adjusting tool from one of the parts suppliers and adjust the mixture. I got mine from Terry's. You may find instructions by searching this forum, but I found them on the jag lovers forum. Good luck!