My Mother-In-Law got nostalgic early this year and purchased a 1976 280S twin cam 4BBL six. The car has 78000 miles on it and is in decent cosmetic condition for its age. Unfortunately, she has not been able to find a competent mechanic in her area that can get this car to run and idle right.
Up to this point, it's had: Ignition tuneup,by a 'trusted' garage on Ventura Blvd who charged her 50 bucks for a 7.00 gas filter, $419.00 for $215.00 (retail) worth of parts, a carburetor rebuild by a MB shop (who told her after a $750.00 rebuild that "this type of car still needs to be warmed up at least 5 minutes before getting underway").
It still dies in traffic, idles like it's got a vacuum leak, and gets 12 mpg (carb set rich to compensate for vacuum leak?).

I'm going down there in 2 weeks with my tools and MityVac tester and am prepared to tow it up to the Central Coast area if I can't troubleshoot it there- at least I'll get it away from the gaggle of grease monkeys that can't fix this thing.
It still has a leaky exhaust manifold and a shot diverter valve in the smog pump system that makes a horrible noise, but NOBODY seems to have noticed this. Instead, another hack has tried to sell her on replacing the intake manifold to make it run quieter!

My questions to all who have been so helpful with my 300D--
1) This engine is not rocket science, but is there anything tricky I should watch for in diagnosing this inability to idle?
2) it has the California A.I.R. pump- I believe this car does not need smogging due to its age- would it hurt the carb settings if I just yanked all that stuff out?
3) what type of fuel economy should I expect from this twin cam (city & highway)

Thanks in advance for your thoughts and assistance! (she should have got a diesel IMHO- I love mine much more than she loves hers!)

Nate Stanley
'79 300D
'85 F-250 6.9 diesel