Heres one for ya . I have a set of small block heads 186 castings , they will not hold a head gasket for nothing . Ive put them on two differnt 350's and tried 2 differnt gaskets the first was fellpro economy you know the blue ones tried 2 sets . then tried the fellpro 501D severe duty gaskets 2 sets . i keep getting coolant in the cylynders usally an passenger side , but olso #3 . Both blocks are fresh decked and flat i know i checked them a dozen times . The heads are fresh from the machine shop and also flat i checked them to . the shop said he took
.020 off them . they were magged and had a valve job also . Is it possible theres not enough metal left between the outer water passage and the combustion chamber .