Maybe this is common but I don't recall seeing a post on it. I noticed that one of my rocker stand mounting holes is drilled and tapped into the cooling passage. I know there are other bolt holes that do this as well (intake). Could cause someone a lot of aggravation with coolant getting into the oil with no obvious cause. Mike

The way I found the hole.

Someone had stripped one of the rocker stand mounting holes. Their repair consisted machining a flat spot approximately .040" deep around the hole. They then drilled and tapped the hole to 1/2" 13 all the into the cooling passage ( not the hole I refer to above). A 1/2" 13 bolt was threaded and sealed into the head. The bolt was then drilled and tapped to 5/16" 18. Rather than machining down to original pad height the bolt was left as is and the rocker stand was notched to go up and over the head of the bolt. Very creative! After the repair to this hole I was checking the rest when I found that one was drilled through.

1956 Fairlane Victoria (ORREO)

 

Overlooking Beautiful Rimrock AZ