painting the engine, shiny valve covers and chromed engine tins etc. a good idea? here is what Bob hoover says:
..A light coat of flat black paint on the magnesium-alloy crankcase not only protects it from corrosion, it enhances the heat-flow characteristics of the surface. The cast iron cylinders benefit even more, although they are more difficult to paint. The trick is to get the paint right down into the bottom of the fins. To do so calls for the use of a suitable brush, made by cutting off half the bristles from a small (1/2") paint brush; not an artists brush, the regular sort does fine. You must use a brush instead of spray because by the time you've sprayed enough paint to reach the bottom, you've flooded the upper part of the fins and made an unholy mess. So start with the brush, take your time and give your new jugs at least a day to dry before handling them.
High time engines, especially those operated in cold climates where corrosive substances are used for snow removal, are often found to have virtually no fins at all when the engine is torn down for rebuild. Ions of the corrosive material, common rock salt in most cases, attach readily to unprotected cast iron, and once attached are impossible to remove without boiling with a 'getter.' This means that once the corrosive ion finds a home on your cast iron cylinders, the corrosive action will continue year round, thanks to water vapor in the air.
Rusty or corroded metal makes a fine heat insulator, as every weldor knows. A few ounces of paint judiciously applied prior to assembling your engine is not only the mark of an experienced mechanic, it is one of those tricks so simple it is often overlooked. But in the long term it means greater service life and lower operating cost.....
Veedub drivers in cold climates have long known the benefit of chrome plated valve covers and pushrod tubes. The heat-reflective surfaces cause the engine to run from ten to thirty degrees hotter.
The original Volkswagen engines (1935-37) was designed for a service life of 100,000 km; it didn't even have replaceable bearing shells. But through the use of full-flow oil filtration systems the service life of a properly assembled VW engine can exceed 300,000 km, which means the engine may be exposed to the elements for 20 years or more, and that justifies a protective coat of paint.
Flat black paint is virtually transparent to heat radiation. Giving your crankcase, pushrod tubes and valve covers a coat of flat black paint atop bare metal actually promotes engine cooling. One of the quickest ways to spot a professionally built engine is from its somber flat- and matte-black surfaces.
Do not use a hi-temp paint as the high clay or eutectic metallic content forms a nice insulator. What you want is a surface that will radiate heat. Polished surfaces reflect heat. If you polish your crankcase it will run considerably hotter than normal.