Cylinder Head Refinishing

[Miniac]

Is there a "proper" method for refinishing a cylinder head? The cast iron cylinders are easy, . . . just spray too much shiny black paint on them and they'll have that factory new look. But after a trip to the blast cabinet it seems like there must be some kind of protective coating of some sort for the heads. Help me out, guys, . . . I'm depending on you.

-kevin

[MSZ]

Bare aluminum...

[Miniac]

Originally Posted by Pony Express

Bare aluminum...

Well that makes it easy, . . . that's what I've got.

[Art]

There was a dip we used for aluminum castings at work, called "Aladine" (sp?). Protected the castings from oxidation, sealed pinholes...
Some were known to sneak in aluminum intakes and dip them.

[racerx]

I'm a bit leery of dipping the head castings. Valve guides and that integrally-cast steel "skull" are critical pieces. Strong acid or caustic solutions could cause problems. That said, there's no reason why you couldn't carefully apply such chemical solutions to the outside surfaces only. Sometimes, the results are amazingly good. Soduim hydroxide works well, but you've gotta be careful and work quickly to remove all traces of it and get the casting dry.

Frequently, heads are deeply stained (and etched) beyond the point where the factory as-cast appearance is gone for good. Fortunately, glass-bead blasting gives a very acceptable result for this part. Once the engine back together & running, normal cleanings of the oil & road dirt that accumulates while riding actually make a bead-blasted head look more "original, as-cast".

[Miniac]

Originally Posted by racerx

<snip>
Frequently, heads are deeply stained (and etched) beyond the point where the factory as-cast appearance is gone for good. Fortunately, glass-bead blasting gives a very acceptable result for this part. Once the engine back together & running, normal cleanings of the oil & road dirt that accumulates while riding actually make a bead-blasted head look more "original, as-cast".
<snip>

In a very recent conversation with a friend (whose head is the one currently in question - looks great after the visit to the bead blast cabinet) I mentioned a head that I did last summer was looking pretty good after it burned off the initial oily coating that remained after assembly. That's usually the closest thing to a "treatment" that they get from me, but I was curious if I was committing a grevious error by not applying some kind of finish. I know that "way back when," Yamaha made a high temp clear spray that was for spraying aluminum engines, but the rumor mill back then said it was just a good quality clear lacquer. I've used it (the Yamaha stuff) and it gets a very slight, almost imperceptable, yellow tinge after a few rides, but corrosion is eliminated. I also know old timers (Yeah, even older than me!) who swear that you just spray the fins down with Pledge every time you wash it and life will be good. I suppose you could use lemon fresh scent and all the bees in the neighborhood would follow you around. Actually, the idea of chemically treating it isn't bad as long as the chemicals are not reactive with cast iron or bronze/brass, but I have no idea which chemicals those would be, so I think I'll stick with the tried and true, "blast it and forget it" method.

Thanks for all the input. This is interesting stuff!

-kevin