Triumph Bronze Head

[alianco]

Hi Martin, I'm sure you're right about the valves, it was thirty years ago. I'd be interested to see the picture you have, but like you I can't see how to attach a photo or I would put up one of mine in its last guise. Maybe someone more computerate could advise.

[Revband]

Open an account with photobucket or similar, free of charge, download the picture and copy the image code on here, the picture will appear as below. .

[VintageBike]

Here's how you attach a picture.  Reply to the post as you would normally, and at the bottom left of the screen you will  see an "Addditional Options" button.  Press this, and you will find the attachments option.

Cheers

Nigel

[alianco]

Here (I hope, following Nigel's instructions) is my Tiger 100 with bronze head and McCandless swinging arm conversion. The seat was from a cossack since their industrial rubber ones were more comfy and didn't disolve like the pattern ones after a year. The two-into-one was stainless for all weather riding and no garage and the brooklands can was just a bit of fun. The purists may well have a heart attack, but it was year round transport and apart from poor brakes, dull lighting and a rather flexible, bolt-up frame it was a great bike. Cheers.

[Martin_UK]

Many Thanks Nigel,

Alianco,

Here's the pictures of the one I saw for sale.

Kind Regards,

Martin

[alianco]

Hi Martin, Yep, that's my bike, FBP 627. So it didn't end up as a vintage racer after all. Pity, I rather liked the idea of someone thrashing it around the track. I certainly would never have the bottle to do it. Apart from the pipes, silencers and seat it looks pretty much as when I sold it. If you look closely at the rear shocks you will see a bright ring below the spring. When the old ones went west I could only afford a special offer pair for a much lighter bike and it virtually bottomed out so I turned up two, thick aluminium blanks to pre-compress the springs. They must be over twenty years old now. Can you remember where you saw it for sale? I'd love to know what happened to it.
Cheers

[Martin_UK]

Alianco, I'll PM you the email address of the seller so you can contact him direct. Kind Regards, Martin.

[alianco]

Thanks Martin. I emailed him and it turns out he swapped it with a mate in the UK for a Vincent in bits. Who knows, I may even get to have another go on it.

[biggles]

Hi Alianco, An interesting story about the bronze head tiger you had. Great story, particularly about your travels and the Post war Brands Hatch history. I often look at this site and enjoy the comments about `is it or isn`t it a bronze one. Please don`t scrape heads with a pen knife, particularly if the owner is in the near vicinity!!!!!. I can help you with some of the history. It was indeed swapped for a dismantled HRD Vincent, a series A Comet that was accidently discovered in a municipal dump at Hayes in Middlesex,found 2000, cost £40 and swapped two and a half years ago. I am very pleased to inform you that FBP 627 is alive, taxed and MOT`d and well cared for up in the Chiltern Hills. Please leave message as i am very interested in any historical details of this machine. You may well be able to sit and ride this bike again if we can arrange it. I will try to post photo of what it looks like now and i have a copy picture of it with siamese ex/p and Brooklands can that was passed onto me.  Regards, Biggles

[runesika]

I have just had my bronze 39 T100 cylinder head vapour blasted and it looks stunning , it's removed all the old staining and burnt on oil .
The bronze heads were originally painted black when fitted in 39 but after what it cost me there is no way it's going back to black !

[Martin_UK]

Have to question the statement that Bronze heads were painted black originally. I've seen pictures of original bronze headed bikes with no sign of paint on the heads ? Also Bronze heads were claimed to aid cooling due to the better heat dissipation properties of bronze, so painting them would surely defeat the object ? Heads and cylinders weren't originally gloss finished as they are now or powder coated, and I don't see how cyclinder blacking would adhere to the bronze ? What original documentary evidence is there to support the theory the head were painted ?

[R]

Bronze would be fairly easily chemically blacked though, using a sulphur compound like artists use for bronzes. This would prevent them corroding to a green finish in any humidity, and assist heat loss.

Although they do look spectacular in freshly cleaned finish.
There is also several things they could be dipped in to preserve the bronze looking finish - period photos may well show how they looked in b&w photos, which would give a clue.

[runesika]

I have spoken to someone who has owned two bronze heads for a 39 T100 and he said both were black or black paint stuck between the fins .
My bronze head also needed the old paint removed from between the fins before i could have it vapour blasted .   I have seen the racer T100 in the picture you have posted and know it was an original bike ordered with a bronze head in 1940 but it would have been pulled down and cleaned up a few times in its racing life ? 
I am not 100% sure that they were painted black but i think they must have been , i think the people who paid their £5 in 39/40 would be just as keen to show it off as i am and maybe most were polished up for looks .

[33d6]

I think pride of ownership here is ignoring basic physics. The bronze head was an interim step between the cast iron head to aluminium alloy as we have today. It only existed because it could get rid of heat a little bit better than cast iron. If it was black it worked even better. Polishing it reduces its ability to shed heat. Dark surfaces radiate heat much more than shiny surfaces.
The theory behind the bronze head was that better cooling meant that when running on petrol you could raise the compression ratio higher than was possible with a cast iron head. All things being equal, a higher compression ratio gives more power.
Obviously if you blackened the head you maximized its ability to shed heat so the compression ratio could even be a little higher.
If you want to take advantage of the reason the bronze head exists, blacken it. If you just want show what you have keep it shiny but only run the standard compression ratio.
Cheers,

[runesika]

Hi ,  Yes that's all correct  Even though i am sure they were black from the factory this is the one thing i will be happy to be "wrong" .
My bike is used for ride outs and sunny days and is not used for classic racing , as i dont need to squeeze the last drop of power from it i am more than happy with my "blingy" head .   Horses for courses as they say .