I have looked a two sites with peach parts being one of them and found that the 116/117 engines take a flat seat spark plug like the W9DC or BP5ES.

The 103 in the 300SEL takes a HW9DC or BP5EFS tapered seat plug.

So the 116/117 have the flat seat with a crush washer which is the BP5ES.

The 103 has a tapered seat which is the BP5EFS.

Are we discussing the same thing from different angles?

I think xaliscomex needs NGK BP5EFS taper seat plugs

I believe a gap of .030 to .032 inches will work great.

PaulM

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84 500 SEL (307,xxx miles)