On my flathead Tecumseh, whose clearance was too small, I had to grind the back of the valve stem, to increase the clearance.Ĭan you check the valve clearances, at least? They were fairly easy to check on my Tecumseh, hopefully that's the case here. The adjustability is typically provided by the OHV mechanism, having that rocker arm that can be tightened/loosened. Valve clearances not being adjustable sounds typical for me, for a flathead engine.
