This I simply don't understand. I put a rebuilt Motorcraft 2150 2v carb on my 1977 F-150 400m Engine, and then set about adjusting it per the tech manual. I had only one problem: when in "park" the idle was fine, but when I put it in "drive" the engine died. Ok, fine, call for help. I contacted the local carb expert and he said one phrase: "weak idle". The mixture was too lean. So I adjusted the mixture properly this time (yeah I screwed up), and it worked great!
Now the question: why?
Why does a load on an engine with a lean mixture cause the engine to die?
Thanks,
Cy