I just found a photo...

Simon Dinsdale

VOC Machine Registrar
VOC Member
VOC Forum Moderator
Hi fonusbak,

This thread is really interesting. My dad has the remains (80%) of a 250 Rudge which is almost identical to the one in your photo. The fuel tank has the hand change and the oil tank is inside the fuel tank hense the twin caps on the tank. We have never seen a photo of a Rudge with the same tank and so he was never sure it was correct. Most photos show a oil tank under the seat between the rear mudguard and frame down tube.

The cylinder head is a thing of beauty (or complication) with the 4 valve radial configuration. My dad did join the Rudge club, but due to illness has not tried to find out exactly what he has.

Would it be possible to send me a higher resolution scan of the photo? If so I will send you my e-mail via a private message.

Cheers,
Simon.
 

Tom Gaynor

Well Known and Active Forum User
VOC Member
Four-valve Rudges

Answering another query first, the combined petrol / oil tanks were on road bikes. I had one for a while, apparently dated 1932 or 33. Replicas had the oil-tank "wrapped round" the seat tube, similar to a Manx Norton tank. I actually have one of those.
I haven't time to dig something out now (off on vacation tomorrow), but it's easy to explain how it was done.
The four valves were placed radially, so that if one pushed rods into the guides, they'd all meet at the same place, near-as-dammit the centre of the hemisphere that was the combustion chamber. Two small valves give a better opening area and better combustion than one big, with less valve-gear inertia, so four valves. (The 500 Rudge I raced was safe to 8000 rpm) The radial disposition gave more space between the valve seats than parallel valves, reducing the risk of cracking between the seats (which is relatively common).
On each side, the rocker operated by the pushrod had its axis across the bike (so operated fore and aft). There were two other rockers with their axes parallel to the long axis, operating starboard to port, as it were, i.e. at 90 degrees to the first one. The near end of one cross rocker was in contact with one closed valve, the far end of the other with the other. When the pushrod rocker rose at the pushrod end, it pushed down on the next (cross) rocker which opened one valve with the end going down, while the other end rose (see-saw) and raised one end of the last rocker. At the far end of the last rocker was the other valve which was thus opened. It paid to make the remote valve "lead" the near valve by about 0.006" to take up any slack in the train so they opened simultaneously. Everything ran on needle rollers, which require very little lubrication. Assembly however was (was? It still is!) finicky.
Nothing new under the sun: Rudge made four valves work, but so did Ricardo among others before them. Ducati "are" desmo. But Mercedes Benz perfected it first, in their pre-war GP cars.
hi tom. i know this is pushing it but would a few shots of their radial dispositioning be available or perhaps a link to some? i often wondered where honda pilfered their "RFVC" system from and would be interested to see.

does anyone have a good shot of a excelsior mechanical marvel while i'm about it? my magazines from the nineties were storage damaged.
 

fonusbak

Forum User
Non-VOC Member
Hi fonusbak,

This thread is really interesting. My dad has the remains (80%) of a 250 Rudge which is almost identical to the one in your photo. The fuel tank has the hand change and the oil tank is inside the fuel tank hense the twin caps on the tank. We have never seen a photo of a Rudge with the same tank and so he was never sure it was correct. Most photos show a oil tank under the seat between the rear mudguard and frame down tube.

The cylinder head is a thing of beauty (or complication) with the 4 valve radial configuration. My dad did join the Rudge club, but due to illness has not tried to find out exactly what he has.

Would it be possible to send me a higher resolution scan of the photo? If so I will send you my e-mail via a private message.

Cheers,
Simon.

Hi Simon,
the photo is up north at the moment and I suspect thats the best scanner we've got. I'll ask if anyones got a better one.
Phil
 

fonusbak

Forum User
Non-VOC Member
Hi Everyone,
This really is amazing. I'm really knocked out by the interest, the responses and the level of your knowledge is stunning!

I hope you're all enjoying this as much as I am!
Phil
 

Tom Gaynor

Well Known and Active Forum User
VOC Member
Pictures of Rudge radial heads

I've just posted four pics. The fully radial head is from a works TT bike, 1932, and this has the valvegear layout used on the 250. The semi-radial is from a 1933 Ulster. Both heads are from 500's.
 

johncrispin

Well Known and Active Forum User
VOC Member
Vincents get a mention here

This is only of passing interest but is a strong rumour passed to me by a respected authority in the Rudge Enthusiasts club, that Soichiro Honda acquired the patents on the four valve radial layout circa 1947, so from EMI then. Roughly at the same time i think PCV purchased the patent for the handle operated centre stand which was eventually manifest on his series D machines. Merv Stratford once remarked to me that with fierce lift and race cam overlaps there is a severe risk of valve entanglements at high revs. Despite this Merv extracts 30+ bhp from his 250 Rudge racers explaining how he manages to trounce bikes half the age of his phenomenal machines. His website http://www.stratford-rudge.co.uk is well worth a look.
 
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