So I cut apart that "bad" one I did and redid it:
Came out much better - practice.
However I then learnt that welding the outer cooling jacket on distorts the flange, despite it being 12mm thick. It's OK - but for the 2nd exhaust, I bolted it to a piece of plate:
This one came out perfect. I'll make a new one for the other side eventually.
And I also made up a tool for holding the "job":
And welded the AN-10 coolant inlets on:
Not forgetting to purge the inside as well when welding.
Also had to modify the actuator mounting brackets:
And it finally looked like it might all work OK:
So we're now at the stage of trial fitting it all to the boat. You can see the flanges came out OK:
And externally:
Which is where we are now. Next steps are to work out the routing and rigging for the air pump that runs it, along with take it all apart, give it a jolly good polish with my new 1.1kW bench polisher:
Still lots of jobs to do - fix the leak in the sump gasket, finish the new air intake scoop, but it's all good progress.