https://www.cycleworld.com/ajs-porcupines-prickly-history?dom=rss-default&src=syn
This article mentions Phil Irving as a designer as well as Ted Frend, who earned a Gold Star with his A twin at Brooklands.
David
AJS Porcupine History
- Thread starter davidd
- Start date
https://www.cycleworld.com/ajs-porcupines-prickly-history?dom=rss-default&src=syn
This article mentions Phil Irving as a designer as well as Ted Frend, who earned a Gold Star with his A twin at Brooklands.
David
Dear David,
Many thanks for the link. Kevin Cameron's articles are always interesting and informative.
I believe in the early stages silver was considered for the cylinder
head and ajs visited Hatton garden till they found out about the cost!
The piece did not mention a attempt to race a modified porcupine in the UK in the sixties by someone like Tom Arter certainly I saw it in the paddock a few times it was when racing was in the doldrums and all the talk was about a UK world beater by public subscription and anything was tried to perk up domestic racing
head and ajs visited Hatton garden till they found out about the cost!
The piece did not mention a attempt to race a modified porcupine in the UK in the sixties by someone like Tom Arter certainly I saw it in the paddock a few times it was when racing was in the doldrums and all the talk was about a UK world beater by public subscription and anything was tried to perk up domestic racing
I understand silver was used to cast at least one head - and after the trials it was returned to the supplier who promptly melted it down
Pure silver has a thermal conductivity roughly 2x higher than pure Al, which is why an engineer thought to use it. Silver actually isn't all that expensive (today, if an Ag head weighed 5 kg the cost of the material only would be $2.5k), and no matter what it could be returned to a smelter at the end of the season and melted down, so cost wasn't a factor. Unfortunately, materials science was and the engineer with the clever idea to use it had missed that class in his studies.
Pure silver is soft so it has to be alloyed to make it hard enough to be useful, but alloying lowers the thermal conductivity. By the time enough alloying elements had been added to the silver to make it hard enough for holding valve guides and seats in place its thermal conductivity had been reduced to be close enough to that of Al alloys that there was no advantage to using it.
Pure silver is soft so it has to be alloyed to make it hard enough to be useful, but alloying lowers the thermal conductivity. By the time enough alloying elements had been added to the silver to make it hard enough for holding valve guides and seats in place its thermal conductivity had been reduced to be close enough to that of Al alloys that there was no advantage to using it.
Desparate times result in desparate measures.
Oh well, I might as well return those Gold heads I had cast up back to the meting pot then....................
It seems to me there are 3 at the Barber museum, or at least used to be.
