Topic: When did cb750f switch valve guides?

[scottly]

The heat-sinks I'm used to in industrial electronic equipment are black anodized, not painted...

[phil71]

If you think that in the absence of white light, color makes any difference to heat dissapation, you're crazy.

[kmb69]

I'm with Retro Rocket and Phil71 - Color alone has very little to do with heat dissipation.
Color makes a bigger difference when related to heat absorbtion from light radiation.
I think the black F1's and F2's run a little hotter because:
1. They make more horsepower.
2. They run them a little leaner for reduced exhaust emissions.
3. The paint on F1-F2 parts seems to be a little thicker than silver parts.

Just my .02

[70CB750]

One more time.. the color isn't as important as how thick it is.. so if you are planning to put silver OVER the original black, you're just making things worse.

I would be blasting off the paint and go just bare aluminum.

[Retro Rocket]

One thing repeatedly missed here is that black paint absorbs heat faster than other colors, thats a given, but it also radiates heat faster as well , as Scott alluded to, black heat sinks are more efficient than plain aluminum ones for the same reasons mentioned earlier. So color is important to a degree. {no pun intended} 

There is a lot of good information out there regarding this subject....

The ambient light is not important. In the darkness there is no
outside light and it still works. Like this:

 a) Heat is transfered in three ways: radiation, conduction, convection
http://sol.sci.uop.edu/~jfalward/heattransfer/heattransfer.html

Here we will deal with radiation only, and that is controlled by
Absorption and Emission (coefficients of the surface)
http://www.efunda.com/formulae/heat_transfer/radiation/overview_rad.cfm

 For a dark surface, both coefficients are high, and for a white or
mirrored surface, they are both low.

So, imagine N spheres in a vacuum, with temperatures T1, T2,  ... TN
placed in a mirrored box (to eliminate outside light and other radiation).

 The hot spheres (high Ti) will radiate more than the cold ones.
 The hot and black ones (high emissivity) will radiate the most of all.

search teems: Wien's law, Stefan's law
see  also commentlarryg999-ga

 So, even if there is no outside light, the box will fill with
(infrared ..)radiation and, in the long run, all spheres will have the
same temperature.
That's is called thermal equilibrium.
http://www.madsci.org/posts/archives/dec96/835000890.Ph.r.html
 White spheres will take longer to reach it (closed door) but will reach it too.

  In the 'naive picture' (seeprobonopublico-ga on 25 Mar 2006 12:29 PST)
"black likes heat and will attract it," or "hold on to it"  . That picture
contradicts the second law of thermodynamics: In the erroneous
understanding of the effect of color, the black object would hoard
heat and also attract more, and therefore get hotter and hotter.
That's not possible.

 From the above reasoning, we can see that the fact that emission and
absorption coefficients have same values (high for black, low for white)
is not a coincidence. It is a deep consequence of the Second Law -- a
special case of the Onsager reciprocity principle.

It should also be mentioned that silver paints can actually make an engine marginally hotter due to metallic particles in the paint...

[kmb69]

Good stuff RR! Thanks

[phil71]

Even more reason that its not the black making it run hotter, it's the black paint being thicker.
  If anything, the black paint, being it's own material would cool the engine FASTER as it draws heat towards it.
  The engine is far hotter than the ambient temperature, so it SHOULD be cooler based on that article.

[Retro Rocket]

I agree, i think its all down to the thickness of the coating, the newer powder coat systems are very thin compared to the stuff i used to apply in th e1980's, i'm thinking of giving them a try.......

[kghost]

Bunch more fins on the valve cover woulda been a neat trick.

I've always wanted to build some up with the TIG

[Retro Rocket]

Bunch more fins on the valve cover woulda been a neat trick.

I've always wanted to build some up with the TIG

I think casting a new cover would be easier....

[kghost]

Bunch more fins on the valve cover woulda been a neat trick.

I've always wanted to build some up with the TIG

I think casting a new cover would be easier....

Yup. Except I don't have a furnace or sand or a mold......

Do have the TIG and plenty of rod

[Retro Rocket]

And just how well can you use said Tig and rod Tim..?