Springboarding off Lou’s recommendation about cleaning > for the threaded bolt holes use a
thread chaser, not a tap. Here is a video describing the difference and the why
link. Chase ALL the bolt holes, including the exhaust and intake manifold ones on the head. And do not forget to do the non-removed head intake bolt holes, although I am with Lou on pulling that other head and taking both in for a look over.
And like tapping, when using thread chasers, back off occasionally and use a lube. This is covered in the video as well. And thoroughly flush and blow out the bolt holes when done. Brake Clean and compressed air does the trick (wear safety glasses) and if no compressed air while the Brake Clean will evaporate get a couple of those cans of compressed gas used to clean keyboards and dust off things to get out any remaining debris. Having a proper and clean threads if key to a proper assembly and cannot be overstressed.
And do not forget to clean off the bolts themselves again with a thread chaser / wire brush. Better yet get yourself a “kit” of new bolts and gaskets for the Manifold / Risers. And then take two of the old riser bolts and cut off the hex heads to create a couple of studs to assist in assembling the exhaust manifold. They will hold the gasket while you position the manifold onto these studs and make it a whole lot easier. See post #18 of this
link for some more info on this.
Other prep work is to fully understand the methods and torquing requirements for reassembly. One aspect is the low torque values for the manifold, risers and even the initial torquing of the head bolts. It’s like 20ftlb and using a 150ftlb torque wrench is not recommended. I try to target one where the final applied torque is in the 50% - 75% range of the wrench being used.
And speaking of torque, the cylinder head bolts are degreed to their final setting. That means they are (after an initial torque setting) turned so many degrees vs. a final torque value. From an engineering perspective it’s a more precise method of creating the proper clamping force. So you will need a degree wheel, like this one
link. Also here is an older post on all of this,
link.
Finally do your research on proper cylinder head gasket. Others will be able to provide the proper advice on a ‘marine’ head gasket, as I not gone down this path yet.
