The damage looks like it was most likely cause during assembly or dis-assembly. i.e. the scores are in the direction the cam moves when it's removed or installed. It's possible they have been there all along, keep in mind a white metal bearing is there to "absorb" hard particles. The majority of the time the cam is spinning on a film of oil and not touching the bearing at all.

I think what Volodkovich is getting at is if the base circle of the lobe was too big it might have scored the bearing on the way in or out. Could be a number of things, debris during assembly, rough handling. If in doubt, measure everything and sit and think about what it's all supposed to do.

You'd usually have a second cooling circuit for the water air intercooler. i.e. another radiator and a small pump. If you use water out of the engine cooling circuit it'll be hot and heat the air unless you're running really high boost.

Yes, I hope he's alright.

Have a read of this and it'll all be clear http://datsun1200.com/modules/mediawiki/index.php?title=Castor

Basically it handles better if you shorten active length of the castor rods a bit.

I second throwing away the machined ones. Machined threads are not as strong as rolled threads and unless they've been very careful on the details there might be stress concentrations where it's been modified.

Stress concentrations are sharp edges, nicks, gouges etc that can be left by machining/ poor design. In highly stressed parts these details also tend to initiate fatigue failures which generally give you no warning before they let go. It's pretty hard to spot a crack on a thread! Pretty dodgy if the stress is high enough to cause failure (which it is if they've broken before like Dave says).

There are better ways to adjust the castor anyway. Check the wiki if you're interested.

https://www.facebook.com/groups/1200fanclub/ as mentioned above is the one I follow/ visit. Lots of people from here on there.

Mine are also gone, I'm guessing it's everyone...

It's been a long time since I posted but I have made some small progress. I made the flanges for the upper part of the manifold on my new little mill. I'm learning so I buggered it up a bit but it's still serviceable. Now just the plenum, pipes and manifold flanges.

One side has a recess cut to hold Orings, the idea being I can easy pop it off to get to the rocker cover/ rockers etc.

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That should be fine in my humble opinion, keep in mind that many modern cars use thermoplastic intake manifolds.

Nice work! If you go for a largish plenum you don't need to worry about flow distribution too much, if the plenum flow area is bigger than twice the runner flow area and the entrances are all nice and smooth and rounded it should be pretty good.