Heres the deal. I heard a pretty signifigant tick on my starboard engine which I thought was a stuck valve, took the valve cover off and looked for the obvious. I then decided to take the easier route and pop of the exhaust elbow and riser hoping it was just a bad gasket. I replaced the gasket between the exhaust manifold and riser, and also the riser and elbow. Started it back up and bingo....no tick!

Here the problem, in the process of doing this I damaged the gasket between the manifold and an adapter plate that sits between the riser and manifold. The manifold has an exit that is a square flange then the adapter changes it to a larger rectangular size which then mates with the riser.

I have no idea how the adapter plate was held on, the two most forward bolts on the manifold line up with the adapter plate however the two rears do not. When I took it off I had to drill out some kid of threaded stud the previous owner used, but there was no head on it. If you look at the picture of the adapter installed that was before I drilled out the studs, as you can see no heads on the studs.

Top of Manifold


Bottom of adapter plate


Adapter Installed


Riser setup

No ideas of how to mount this adpater? What about using a liquid gasket material and threading in studs on one side with thread locker?

Looks like they may have been internal hex cap screws, picure #2 looks like there is a shoulder. When installed the head of the screw would be flush with the plate.

+1 - it does look as though there was a hex opening on the top.

The studs have a female hex. You start the nut on and then hold the stud from turning as you tighten the nut....as I remember.

Yup, it turns out it was female hex nuts that worked. When I took it off I had to drill them out, so I wasn't really sure what was in there to begin with because they where pretty deteriorated.