Racing Engine Protection - Parts Coatings

Although Tech Line offers a number of other coatings, the two previously mentioned, CBC2 and DFL-1, perform most of the duties for the racer doing his own coating. Both are water-soluble and are baked to 350 degrees for curing.

The first step in coating parts is to get them clean, something that requires solvents that leave no residue. Tech Line says to use lacquer thinner, acetone, or alcohol. Non-flammable brake cleaner is another option. It is available in spray cans at auto parts stores. Any solvent should be used with good ventilation.

When working with a used part, after it is cleaned, it is a good idea to bake it at about 150 degrees F for half an hour. This lets the solvent cook the gunk from the pores of the metal. Then do the sandblast number on it.

After a part is cleaned, it should only be handled with a clean, cotton-gloved hand. The oil in your fingertips can affect the adhesion of the coating.

Once parts have been fully cleaned, they must be sandblasted. This is not rocket science, but a little care must be used. A gravity feed spot blaster is available from Northern Tool and Equipment for about $30. This unit is sufficient for gently blasting the parts. Keep the pressure at only around 45 psi. The idea is to only etch the surface, leaving sharp edges for the coating to adhere to. In this light, use 80 to 120-grit blasting sand. This is not the same as 80 to 120-grit sandpaper. Such sand is available where sandblasting is done. If you go in with a gallon can, they might just give you that small an amount. Whatever the package, keep it sealed. Moisture will keep the sand from flowing properly.

On the piston, mask off the ring land area from the top of the piston to the skirt. Ordinary masking tape will do, however I like the blue masking tape for its ease of removal with little residue. Mullinex offers one trick for working on a set. Wrap a piece of paper around the piston, not too tight. Tape the paper together so you have a slip sleeve. One direction covers all but the top; the other covers everything but the skirt.

Use an airbrush to apply the coating. This is a tiny spray gun. It is much easier to apply a thin coat with this than with a regular spray gun. Again, Northern Tool sells an airbrush for about $10.

In spraying the coating, you only want a thin coat, about 1 1/2 thousandths of an inch. No, you don't need a spray micrometer. Spray a light coat and when the color covers the part that is about right. Remember, you are not painting a car.

Going to our first project, a piston, we will use two different coatings. The DFL-1 will be applied to the piston skirt for friction reduction. CBC2 will be applied to the piston top as a thermal barrier. Though not a difficult procedure, practice on a scrap piston first.

Now that you have a coated piston, you are ready to bake your aluminum cake. For small parts-a piston or two, some engine bearings, or a few valves-a toaster oven will do fine. When coating the combustion chambers in a cylinder head I suggest sending your partner to a far away store. This will allow you time to use the kitchen oven to bake a pair of cylinder heads. Combustion chambers get the same CBC2 as the piston tops. When doing a cylinder head, tape over the small holes in a gasket, then use it for the mask of the head's surface.

All the coatings bake at 350 degrees F for about an hour. Parts coated with DFL-1 should be burnished, that's rubbed gently, with 0000 steel wool. The coating can almost disappear. The friction reducing material is imbedded in the pores of the base metal. On close-fitting parts such as engine bearings, the 1 1/2 thousandths-thick coating will burnish back to about 0.0002 inch.