Rocker stand hole through to cooling passage


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By YellowWing - 15 Years Ago
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.
By Ted - 15 Years Ago

Rocker stand bolt holes being open to the water jacket is not common but it is something that must be watched out for.  In your case, it sounds like it happened when the repair to the head was performed.  I’ve found it on Y heads that more than likely happened when someone had tried to tighten the rocker bolts on threaded holes that were not thoughly cleaned of oil or sludge and subsequently broke the casting at the bottom of the hole by hydraulic action.  When I come across this, I simply use a stud with some sealer on the threads to keep any potential water leakage at bay.