Computer scan of Norton Combustion chamber

Fast Eddie · Aug 3, 2017

SeeleyWeslake, contact Dave Degans, he will be able to get it done for you, you could also discuss further tuning ideas.

I tried the NRE heavier springs and they had a profound rev limiting effect!

jseng1 · Aug 3, 2017

Chris said:
Hi

Pip Hingham? the sprinter was the first person I read about doing bronze skulls that was in his drag race bike one of the GS1000 type bikes although I dont know what capacity it ended up at.
Dave Degans would be the man to ask but I am sure he wont give you the namme of who did his skulls.
However I do remeber being told that someone in the vintage club did this to his bikes. I cant remember the bike this was done on!!! but it was 50s eraor earlier.
Will post & ask on the BHR site.

ps The Daytona with 4mm valve stems, offset ball lightened rocker arms, light weight followers & springs with less poundage resulted in an engine where the cam did not get worn out. Dave told me the race springs sold with higher spring rate pressure caused lots of problems & wore out cams quickly. ie every second season.

Chris

Chris - do you have a photo or can you explain the offset rocker arm ball?

Fast Eddie - interesting to hear of the rev limiting effect of heavier valve springs. It takes HP to compress those springs and I'm always concerned about wasted energy of heavy or high pressure valve springs but I've never heard of such a dramatic effect before. I recently went through a lot of valve spring research with manufacture techs and it all points to the same thing with one best option.

Seeley Weslake - I think Triumph have more overheating problems than Nortons. Note the smaller fin area of Triumphs. Haven't noticed the Nort heads going soft in use but overheating is definitely a problem with high performance Norts.

acotrel · Aug 3, 2017

With my 63mm stroke 500cc Triumph motor, the cams were very long duration, slow lift rate and not as much lift as with E3134 cams. The rev limit was about 10,500 RPM and it never had valve bounce. The problem was the power band was very sharp and lacked mid-range, but when the bike was wound out down very long straights on big circuits, it became frightening at the ends of the straights. The bike badly needed a 6 speed CR gear-box. Most of the crashes I have had while racing have been due to the drum front brake. If you want a really big crash, that is the way to get it.

Chris · Jan 5, 2018

Hi Seeley Weslake
I have had a message from a friend ie who does bronze sculls & will phone him at the weekend to get soe details if you still need this info?

All the best Chris

Ps Jsing just noted you asked for a photo of the Degans offset rocker arm, I will take a photo as they are still in the garage somewhere & post asap.

Momus · Jan 5, 2018

jseng1 said:
I would rather pour some molten alum into the combustion chamber and machine from there. Let me know more about your skull experience and describe how it is attached and if there are heat transfer problems etc.

Bronze Skulls sound like a lot of machining - the head and both surfaces of the skull.

Welding will soften the metal but you can quench the head in boiling water immediately after welding when its hot and heat treat it in an oven for several hours at about 375 deg F. I've done that for cases and it age hardens. What did the factory do after casting?

The alternative to welding for me is to pour molten alum into the port floors (with conical anchoring plugs) and then re-port/re-angle valves from there.

Hammer peening the welded area when warm is helpful for getting things nice and hard.

acotrel · Jan 5, 2018

If I was going to do what you want to do, I would work with Ken (Fullauto) to get a new head casting with provision for your changes to be machined into it.

SeeleyWeslake · Jan 5, 2018

Chris said:
Hi Seeley Weslake
I have had a message from a friend ie who does bronze sculls & will phone him at the weekend to get soe details if you still need this info?

All the best Chris

Ps Jsing just noted you asked for a photo of the Degans offset rocker arm, I will take a photo as they are still in the garage somewhere & post asap.

Thanks Chris - Have PM'd you

Computer scan of Norton Combustion chamber

Fast Eddie

jseng1

acotrel

Chris

Momus

acotrel

SeeleyWeslake

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