Download Building a VW Engine

Prepare a 1" wide bristle-type paint brush by cutting away half the bristles at the ferule.
What you need here is a brush having bristles as long as those found on a 1" brush... but
only half an inch wide. And no one makes such a thing at a price you can afford. (I use
those cheap Chinese brushes, purchased a carton at
a time, discarding the brush after use.)
Mix four parts of flat-black Rustoleum (brand name) paint with one part of thinner and
use your long, narrow brush to apply the paint between the fins, reaching all the way to
the bottom.
Is this coming across? Probably not :-)
Your jugs are cast iron. They are going to spend the rest of their natural lives hanging
around the nose of an airplane, maybe in a hanger if they're lucky but for most the best
they can hope for is a leaky canvas cover.
That means they're going to rust. And rust is a very good insulator, as any weldor will
tell you.
If you build a proper engine it is going to cost you at least a couple of thousand dollars...
or a couple of hundred hours of your time. Or both. The paint is an inexpensive way to
protect that investment and to insure the engine will work as well as it should.
Why the modified brush? Because you can't spray paint between the fins. By the time
you get enough paint on the bottom you'll have runs all over the place. (Go on; try it.) So
you need to apply the paint with a brush. But you can't use just any brush; it must be a
small one, in order to fit between the fins, but the bristles must be long, in order to
reach the bottom of the fins. And while there are such brushes artists and sign- painters
use them they are not commonly available and are very expensive.
As for thinning the Rustoleum, paint forms a thermal barrier, the thicker the coating the
better the insulator. We want to use the thinnest coating that is practical to apply...
which works out to about a 4:1 mix. (You are the Mechanic-in-Charge experiment with
the mixture and use what works best for you.)
Why Rustoleum instead of high temperature stove paint? Stove paint derives its hightemperature properties from clay or metallic salts, both of which make wonderful
insulators even in a very thin coating. If you use such paint on your cylinders or
crankcase it will cause the engine to run hotter than it should. Plus, high temperature
paint isn't especially good at protecting the surface from rust, as the owner of any
barbeque or wood- stove can tell you.
And finally, the jugs don't get hot enough to require a high temperature paint.
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