Well, there are some similarities -- they have to be done correctly and nothing is exactly cheap...

Those are the chokes. Probably electrically heated, check the wiring and make sure the heaters work. Should, like any automatic choke, snap shut when below 70 F or so, open some at full throttle position, and open up slowly as the engine heats up. They must be fully open while you adjust the carbs, of course.

Some of them were water jacked heated, but I believe the Zeniths were all electric. Check linkage to make sure someone hasn't fiddled them to "fix" a bad heater issue.

Also verify that the manifold heat risers under the carbs aren't stuck. They usually stick open, roasting the carbs and can actually warp them. I'd lock them closed myself.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!