May 23, 20169 yr Hi all, I'm about to mate an EJ251 from a 2000 Impreza RS to EJ25D heads from a '98/'99 Outback. I was told to utilize the head gaskets from the EJ251 (very thin) to bump up the compression. I was also told that I needed to use copper sealant on the HG's. I'm not sure why, the shop didn't have the time to explain to me... Looking around the other subaru forums, I've not seen any mention of copper sealant being used for ANY application, be it stock or hybrid. Ideas? Is there a difference between the Permatex Ultra Copper RTV and Copper sprays? The RTV states that it is rated for 700 degrees farhenheit. . . Take care, Greg.
May 23, 20169 yr Never use any selant on headgaskets, they are always installed dry. Proper block prep and head resurfacing is key to getting the right seal and there is no subsititute
May 23, 20169 yr ^+1 I'd also do some more research on the HG to use. I 'think' the STI EJ257 HG is recommended. Too thin and you may have piston<>valve issues?
May 23, 20169 yr 11044AA642 04-06 sti is the head gasket of choice for this build. The ej251 gaskets are crap, and will blow in fairly quick fashion.
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