I have to say that I've been running for a couple of years with a 4 degree offset that corrected for my stretch.

With 300k miles on the engine, I recently decided to roll-in a new chain (with a 0 degree offset key). The car runs MUCH better. The only difference I can figure is that it corrected the IP timing, which is uncorrected by a camshaft key.

While I had not checked the timing of the pump before installing the chain, when I drip-tested it right after, it was dead on 24 degrees. Perfect.

One other thing an offset key will not help is wear on the sprockets from a stretched chain.

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1981 300TD 310k miles
1970 280sel 172k miles
1966 230 Fintail 162k miles

"Where are we going? And why am I in this hand basket?"