Marshall: Thanks for the information. I see now, the chain stretch for a 606 is checked at #1 TDC before the power stroke. The little hole in the drivers side cam gear lines up with a hole in the front cam journal. It takes a pin larger than 5 mm, but smaller than 5.5 mm to verify alignment of those holes. I inserted a 5 mm allen wrench and tweaked the crank shaft until that wrench was level. The 1.5 mm holes in the two cam gears, that align at the indexed position, are not drilled through. I could see them. today, in the daylight and wearing reading glasses.
Final result: Chain seems to be streched about 4 degrees. Disappointing since this engine is only at 143k mi. Maybe the PO's were not that particular about oil changes during the first 100k miles. Ned Kleinhenz
