Time to assemble the valve train, comprising the rocker boxes, valve springs, rocker arms and camshaft.
Here are the rafts, including the camshaft (still in development when this was taken) and the already-seen cam tower raft (as it turns out, unused in this sequence.)
The camshaft is required, as the lobes determine the valve spring compression. The rocker boxes are assembled by sliding them over the camshaft. I should note that in this preproduction greybox build, these are not the final versions of the rocker boxes either. As shown I have drilled out the bosses where they mate to the cylinder head studs; this is not necessary with the production parts.
The rocker boxes are not glued up at this stage, just dry fitted.
Instead, the rocker boxes are glued to the studs on the tops of the cylinders, one at a time, starting with the rearmost. I used epoxy on the rear rocker box to give me time to jiggle it into alignment. The remaining boxes were secured with CA.
The valve springs come on rafts like this. Obviously a little bit of care is required to remove them, but it's not terrible.
The springs are simply inserted into the valve guides. It's important to chase the valve guides with a .35mm drill bit beforehand. Preferably this step should be performed before assembling the cylinders. With the valve guides properly cleared, the valve springs easily do their thing and bounce up and down.
The rocker arms are assembled with the followers on the cams so that they are correctly open or closed depending on the rotation of the camshaft. It took me awhile to perfect the technique for this process. In the end, I found that securing the rocker in its trough with a drop of watered down future worked best. Also note that in this test build I was experimenting with resins for the rocker arms. This white stuff is very strong but prints a little on the rough side. I discovered that the rocker arms aren't as delicate as I feared and therefore could be printed with the really high fidelity stuff.
The rocker box cover then just drops in place. These are pre-production parts; the production version has pins for the cover.
The whole thing assembled...
On to the painted version, for which I used the final production parts.
Here you can see the pins for the rocker covers.
Here are the production rocker arms rendered in high fidelity resin. I didn't break any assembling this thing; the real danger is mistakenly cutting away the wrong elements when removing them from the raft. I'll try to make it very clear in the instructions what's sprue and what's actual workpiece. Again, the technique I found that worked best was to cement the rocker shaft in its trough with watered down future and holding it in place until it sets up enough to resist the valve spring. I decided to paint the rocker arms after assembly, a decision I'm not sure I'd repeat...
Here's a lurid close-up; not bad imo for 1/32 scale...
That's it for now. Next time I'll get the cam drive tower assembled along with various ancillaries.
