O ring head gasket

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Well-Known Member
HMEM Supporting Member
Dec 8, 2020
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Thermopolis Wyoming USA
I'm building the Hoglet and want to try an O ring head gasket. The O rings I have are 1/16" by 1.25", Viton. The question is how deep should the groove in the head be, how much crush? The rings are about.070" in thickness. On scrap a groove of about .045 seems about right. Or would the best idea be just use a traditional gasket and not risk the heads which already have a lot of work done?
.045 seems shallow. The Farm Boy hit n miss is designed for an o-ring head gasket and calls for a .060 deep groove.
I use O-ring (3/32 to 1/8 in.) head gaskets exclusively on my models in conjunction with the cylinder liner that rises above the deck to cage the O-ring. A matching groove is cut in the cyl. head and block for the O-ring to seat into. Not worried about the crush height and you should see the O-ring between the head and block after torque down. The O-ring is not exposed to combustion gasses for deterioration and just ordinary nitrile plumbers material is used here. The key is the cyl. liner support for the O-ring.