[Episode 9] Build begins with Section 6, Engine block gets a fix

The new build has started, with the engine block – Section 6. I think I chose to start here as I wanted to get into recreating the shims needed to get these parts to fit. The engine block is a key part is checking the fit between the chassis and just about everything behind the firewall (engine, transmission, exhaust, intake, rear wing support, engine mounts).

The engine block is built from a stack of 9 layers made up of 15 parts. in Section 7, the stack gets sandwiched between a base plate (part M304 if you’re playing along) and a top plate (M286).

And so, I found a problem: my initial dry fit of the stack of engine layers shows that the block doesn’t seem to assemble long enough: fitting the stack into the sandwich (picture below left) shows a big gap, later measured at 1.5mm. Test fitting some other components – the inlet and exhaust manifolds – shows that the base and top plates are correct, but the stack is too short. When spaced out using the manifolds, the stack fits in the sandwich (below right), which suggests the fix is to shim out the stack. Spacers are needed faily evenly along the length of the stack of layers.

In the new build I found a similar problem, and others have too, so its a thing with this kit. This time the shims needed to be thinned very slightly, down to about 0.150″ thick each. The same approach was taken as last time…

I decided to shim in four places where the shims would not interfere with the combustion chambers, so the shims will be placed in two groups, between the 1st and 2nd, and the 3rd and 4th rotor. This means they will be attached to parts painted ‘Steel Metallic’ which is a bit darker and should hide them a bit. I tested another dry fit using four 1/64″ scrap shims (1.5mm / 4 = 0.375mm = 0.015″; 1/64″= 0.016″ so that’s pretty close, see below left). The shims will all be the same shape, so I stuck a vinyl template to a stack of 0.016″ thick aluminium plates and made four of them (below centre and right).

Note the template for the shim is in my annotated instructions (Visio file, see page, A – Patterns) on the Documentation page.

One more dry fit with the shims fitted and most of the cleanup of the engine block parts done, and it looks good.

Note that a couple of pipes that fit between various layers in the stack will need some minor mods to fit corretly. There is an oil pipe (M199) which can be bent to be a bit straighter, and the inlet pipe from the turbo (M142) will be lengthened a small amount with some solder.

Some extra photos from the new build showing stages in making the shims:

Right photo, at top: spare aluminium sheet and vinyl templates. Right photo, at bottom, shims cut close to shape and then glued to the stack pieces. Left photo, the final stack pieces, with the shims filed and sanded to match the stack pieces. Both assemblies have also been through the magnetic tumbler for a mild polish.


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