Yeah, and I'd print out this post from Stevebfl. He wrote the mother of all postings on properly setting the timing on a 450 SEL. The car in question on this post is also a '73 model.

gas milage (1973) 450sl

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Paul S.

2001 E430, Bourdeaux Red, Oyster interior.
79,200 miles.

1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron".