stofer wrote:This is an ordinary brass washer, so I figured I could get it in a hardwear store, if I only knew the dimensions.
BTW, the mod I am talking about is the one where you add an extra washer in the OPV to give the spring a longer stroke and hence slacken(is that really a word)it.
The only real dimension you really need to worry about is the thickness of the washer (as this determines the OPV spring pressure...and therefore brew pressure). If you have a round file or a dremel tool (works best), the other dimensions can easily be adjusted (or don't need to be) to fit.
The outside diameter of the washer does not matter (if it is larger). If it is larger than the current one installed - it will just overhang a bit after it is installed but will have no detrimental effect on operation. The outside diameter is unimportant as long as it is equal or larger than the original.
The inside dimension (the hole) if it is too small can just be filed/dremeled out to increase it to the correct size - I used a dremel tool and it took 2 minutes. When I mod'd my Silvia, I found a copper crush washer at the local auto parts store....worked great. It was about 1.75x of the thickness of the original one in the Silvia. Previous to the mod, Silvia was mighty touchy to technique. Afterwards....she was much easier to work with.