the washer acts as a restrictor to help control the coolant flow , I would think you could buy these as restrictor plates in an automotive speed shopOk I just read through every post from the beginning and there is one question that I have that had been asked that had never really been answered. Where do you find an aluminum washer that's 34 mm OD and 27 mm ID. I saw longhandle or who ever said they made them but does it have to be 27 mm ID? What if it was 25mm? Or 20? Is there one that that would work in standard measurements? Like 1" id? And does it have to be aluminum? Can it be copper or stainless steel? I have all the parts but this damn washer. My local hardware stores don't have it, I've called bolt and hardware suppliers, I've looked on line, I would like to know where all you found that washer. At one time it was said here they were being made for $10, I'm thinking that's the way to go. Please can someone give me some answers?! Thanks!