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What a silly argument. How can anyone reasonably dispute that there is a direct relationship between dissipation of heat and the surface area from which it is dissipated? And how can anyone reasonably dispute that by polishing a rough-cast surface, they are reducing the surface area? Just look at a set of sand cast crankcases - the unevenness is pronounced and must amount to a significantly greater surface area compared to the same castings polished smooth. You don't (or shouldn't) need to quote precise figures to get the gist of that.

As for black being a better colour for heat dissipation, this is plain crap. A dark surface will ABSORB radiated heat more readily, but a surface that is trying to get rid of heat generated internally doesn't give a sh!t what colour the film of paint on its outside is. If anything, it would prefer not to have any film of paint but if there is one, the colour is immaterial, as colour only means anything in the presence of light.
 

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In life, we don't always get the exact answer that we want. So, we use the information we have at hand combined with our experience and, hopefully, education and draw our best thought out conclusion. I call it a guess - an educated guess. Heat is heat, metal is metal, physics is physics. Whether motorcycles, electronic components, or stars and galaxies, it's all the same and governed by the same rules. Unless someone thinks they can make a sh!t ton of dosh by scientifically analyzing heat exchange properties of antique castings, I fear an educated guess is the best we are going get.
 

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You're right, in this case it is an educated guess. All the physics mean jack in this case unless it directly applies. I would research, not physics, but how many actual documented cases are there of Triumph engine failures from polishing the cases. I suspect none. I use the argument when people say you can't powder coat chrome because it is too smooth. Well I have coated hundreds of chrome parts with candy colors and have never had one returned for failure. If a blasted surface is, for number sake, given a 100 value, what is the chrome surface number, 95, 80, 60,50? Who knows. Will the powder flake off tomorrow, next week , next year, or possibly never, who's to say. Theory works the same in this application.
The OP doesn't seem to be worried about because he wasn't the one bringing up the debate. Polish them and be happy, your motor looks better than the 4000 other guys who are afraid to do it.
 

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I'd say the various treatments being discussed (polishing alloy, powdercoating metal, etc) NEVER plays an important part in the average person's life as relates to the operation of thier motorcycle.

When you get into the rare air of squeezing the last fractional horsepower out of a salt flats machine or top fuel drag bike, THEN it MIGHT. (and it still might NOT)

Fun to discuss, as long as it stays polite.
 

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It's an interesting topic, and I'll agree that MORE surface will dissipate more heat. However, I can also see that if the increase in surface area is not fins or some kind of optimized airflow heat-dissipating structure, then the random micro-sized texture might actually trap heat and insulate slightly. Also, texture may also increase adhesion of dirt and oil, which may further trap heat.

I'm leaning towards polishing my cases and covers just because they look sloppy. There are lots of little defects from age, but the castings are not matched well. The 2 halves seem to have an uneven edge, almost all the way around. Covers overhang in places, flush in some spots, and under-sized in others. It would appear that there's more than enough thickness to even up everywhere.

Maybe I'm crazy, but I see it as a working piece of art. It doesn't cost me anything but time to mess with the little details that bug me. In 1973, when my Bonnie was born, both morale and cash-flow were stretched and could not allow time for quality workmanship. I'm not saying they churned out junk, but attention to details took a backseat to production numbers.

As I stripped the frame, I also took the time to file away the weld spatter. I'd guess methods for welding (as production of castings) has improved quite a bit since the 60's and 70's.
 

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I'm leaning towards polishing my cases and covers just because they look sloppy. There are lots of little defects from age, but the castings are not matched well. The 2 halves seem to have an uneven edge, almost all the way around. Covers overhang in places, flush in some spots, and under-sized in others. It would appear that there's more than enough thickness to even up everywhere.
VERY typical, as easily spotted right up front, on top, next to the center of the cylinder mating surface. I've never seen an "even" set of cases.

All you really need to check for is the factory machinist's matching number stamps at the bottom, on both halves.
 

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So...if I get the above drift......all black casings is a good thing...right?

Ta Dah!



All stove enamelled and lovely....but just put together for the photo (in case you were asking why it's not bolted together!)

Cheers

KitKat
 

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Funny - I had the covers out today and was thinking about sending them off for painting but the sun was out and boy they did look nice against the black engine..... so maybe I'll get the mops out.

I'm painting mine to hide all the imperfections in a mismatched set of crankcases. You all know the old saying - "you can't polish a turd but you can cover it in glitter".

Perhaps I should send them off to BritSpeed as he's made such a great job of his engine.

Really nice job by the way (sorry bout hijacking your thread)!

Cheers

KitKat
 

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It would appear BritSpeed is a forward thinker!

Just went back to look at his original post and noticed his first step in the rebuild is to connect the crankcase breather hose!

Smart dude. Sure beats laying the bike on it's side and laying on a piece of cardboard with a cell phone LED light and pair of long-nose pliers to connect that sucker up.

Boffins.
 

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The Rebuild looks Beautiful. I would love too Build a TT motor for my 67 T120C. What would it Cost to do one Like yours.
What is the CC/ Hp. now. I bought a new TT in 1966 Great Machine. Thx Cronin11
 
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