Waterneck gasket info needed !
I had that exact problem on my 340 with an Edelbrock Air Gap, and it DID drive me crazy. I wasn't sure whether the surface on the thermostat housing , or the intake, or both were not true. First let me say that I am not a fan of the gaskets that are peal off sticky on one side. I like all paper with a bit of sealer on each side. I tried filing both surfaces a bit to flatten them, and it still leaked. I tried hard sanding blocks and varying grits of sandpaper, and it still leaked. I tried different types and amounts of RTV / gasket sealers, and it still leaked. I also tried to put sealer on both sides of the gasket, let it set up for a few hours, and then tighten the bolts, and it still leaked. I tried different gaskets, and it still leaked. What finally stopped it was a housing with an O ring by billet specialties. https://www.billetspecialties.com/shop-by-department/tstat/chrysler/?F_Sort=2 Try the gasket suggested by @jazak5, but if it does not work, this O ring housing will. You can scuff it with sandpaper and then prime it and paint it if you want.
I had that exact problem on my 340 with an Edelbrock Air Gap, and it DID drive me crazy. I wasn't sure whether the surface on the thermostat housing , or the intake, or both were not true. First let me say that I am not a fan of the gaskets that are peal off sticky on one side. I like all paper with a bit of sealer on each side. I tried filing both surfaces a bit to flatten them, and it still leaked. I tried hard sanding blocks and varying grits of sandpaper, and it still leaked. I tried different types and amounts of RTV / gasket sealers, and it still leaked. I also tried to put sealer on both sides of the gasket, let it set up for a few hours, and then tighten the bolts, and it still leaked. I tried different gaskets, and it still leaked. What finally stopped it was a housing with an O ring by billet specialties. https://www.billetspecialties.com/shop-by-department/tstat/chrysler/?F_Sort=2 Try the gasket suggested by @jazak5, but if it does not work, this O ring housing will. You can scuff it with sandpaper and then prime it and paint it if you want.
