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 Viper Aero Engine and 1920's Wolseley 10
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sam christie

United Kingdom
2994 Posts

Posted - 30/12/2016 :  01:21:14  Show Profile
On the thread "Where were MG Triple-M engines made?....." this new strand has appeared

the yoke above the MMM dynamo forms a simple but effective universal joint, allowing a little vertical movement and also tolerating the dynamo being mounted fractionally off vertical. Out of curiosity, does anybody know what provision the Hispano-Suiza vertical drive had for expansion, skimming of heads and variation in head gasket thickness, or for that matter the earlier OHC Wolseleys?

The top image below is an example in a glass display case in the Shuttleworth Collection. No problems with head gaskets here.

Here are two cross sections of a 1920's Wolseley 10 engine. It is interesting to compare with the aero engine.


Edited by - sam christie on 30/12/2016 01:39:07


United Kingdom
136 Posts

Posted - 30/12/2016 :  09:27:49  Show Profile
I hadn't seen the Wolseley sectional diagrams before. Very interesting indeed. It looks as though the upper part of the vertical drive is splined. Perhaps it is a telescopic section? There needs to be some provision for expansion, otherwise the bevel gear clearance will be different hot from cold.

The cylinder head layout looks very similar to MMM.

Thank you,


Kevin Jones
Letchworth, Herts
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United Kingdom
1845 Posts

Posted - 31/12/2016 :  10:56:58  Show Profile
Interesting to see the use of BTH magnetos. Wonder whether this influenced the decision to use the BTH magneto on the 'K' type MG engine?
Perhaps another indication of the Wolseley/MG link.

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Blue M

United Kingdom
1439 Posts

Posted - 31/12/2016 :  23:52:00  Show Profile
In an article in Motorsport (Nov.1972) William Boddy wonders why Wolseley didn't use the brilliantly simple Marc Birkigt Hispano-Suiza valve layout and instead interposed rockers between the camshaft and valves. The eccentric bushes are also not a brilliant idea and yet they carried on using them for years. Boddy mentions a number of cars using the Birkigt method, notably Stutz prewar, and the postwar Wolseley 4/50 and 6/80 engines plus a host of modern models - Rover,Austin,Fiat,Hillman Imp,Vauxhall etc.
Apart from the vertical drive the Wolseley car engines appear to have little in common with the Hispano derived Viper engine.
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United Kingdom
199 Posts

Posted - 03/01/2017 :  13:56:52  Show Profile
Having spent Friday examining the Wolsley Viper arrangement there is a very obvious reason why they did not use it on the MMM engines. It works absolutely beautifully when you have a big bore i.e. both valves in line are smaller than bore diameter. for the MMM the valves overhang the bores by a reasonable amount. If they were arranged down the centre line of the cam, as is required by the H-S design this would require the bore spacing to increase significantly meaning the crank gets undesirably long for two main bearings, the engine becomes 50% longer along with needing more cam bearings etc. Using the finger followers means the vales can be moved off the centre line so saving space. You only have to look at the Coventry Climax FWB to see the result of single OHC directly actuated valves, surely the longest 1200 engine ever made!

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Blue M

United Kingdom
1439 Posts

Posted - 05/01/2017 :  11:54:03  Show Profile
That makes perfect sense. I see what you mean!
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