This is an ordinary brass washer, so I figured I could get it in a hardware 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.

It is a copper sealing washer having nominal dimensions of 17 x 21 x 1 mm. Actual dimensions are 17.4 x 20.9 x 1 mm. I would tell you to visit a friendly auto dealership where they typically have an assortment of these washers.

I also assume you have measured pressures and are not proceeding blindly. Keep in mind that pressures will reduce over time as the existing spring ages and/or the hard rubber valve wears slightly.

Eric S.

Thank you!
So far I am not proceding at all, just planning. Want to get a portafilter with pressure gauge. Like the idea of building one myself, as some have done, but I'm not sure the time spent searcing for parts is justified by the money saved.

Christofer

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.

Grant

AFAIK the washer is the same as the steam valve washer available here from espressoparts.com.

What I've read on the subject suggests that this washer will need to be made thinner.

As a reference to those that read this in the future, this is the adjustment referenced above:



Swapping washers isn't necessary for post 2005 Silvia models since they're equipped with an adjustable OPV. There's other modifications noted on the Resources page, e.g., how to build your own pressure portafilter.

I was able to find a fiber washer that is about 1/2 the thickness of the stock copper washer - and heat-proof. The inner diameter was a tad small, but I was able to get it on by working it clockwise and "screwing" it past the threads without damaging the washer.

I tested with 2 fiber washers without a gage, and my 'spro tasted funky. So 1 fiber washer and 1 copper washer did the trick for me.