Hardin marine if I recall right. I torque them in a criss-cross pattern and tighten the **** out of them.
I machined the riser's surface on a piece of granite with sandpaper duct taped to it. (my cnc table) and I filed the manifolds surface with a file, took forever and a day. With towels shoved in exhaust to keep particles out.
Original owner had silicone gushing out between all surfaces and it was leakin when I bought it. I did my work to it and used aviation gasket sealer on all surfaces. Well, the sealer just bubbled and melted out once it got hot, I re-torqued on the water last Saturday and saw all the water spots all around manifolds when I got home.
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