Gene101

In the past I owned 2 Tecumseh 4hp horazontal crank engines, they came off mini bikes. Each one had trouble an were rebuilt in shop class. The problem occurred when at the parts store the mechanic told us that those engine had pressure release valves in them an needed to be reset. I thought he meant the flier on the cam. But that is not what he was talking about. I brushed it off thinking I already knew the answer. I was wrong, after both engines were rebuilt, they both blew the crankcase apart within an hour of operation. After more inspection I noticed a passage way between the valves. Smaller than a pencil but extended all the way into the breather box. It turned out this was where the reset I needed to do was. This was in the early 70's an it has puzzled me since that I have never ran across a small engine with the same passage way or met another mechanic that knew what it could have been. Can someone here tell me what was in the hole contained, an how it was to be adjusted? I shined a light in the hole but could see no opening, just that it could not pass anything through it. Being a teenager at the time I just figured I would see it again. Never have, but have looked for it in manuals an junk yards with no luck.