Picture of FN Motorcycle and Engine

[Colin Morgan]

The picture shows a good view of the 750cc FN engine that Stanley Edge said he used as inspiration for the Seven.  

(The bike itself is for sale on carandclassic)

   

[Chris Garner]

Thank you, Colin, for this.
I used an illustration of a fully restored version in my Stanley Edge publication and made reference to Stan alluding to it helping in his design thoughts on the Seven engine.
This is the first image I've seen of an oily rag FN.

[Colin Morgan]

From the advert, the asking price is on the high side? €55,000 is £48,000!

[Graham Barker]

I am struggling to see much in common between this engine and the Austin 7 engine,  This appears to be crossflow overhead valve engine. 
Perhaps forum members with more knowledge of Stanley Edge's design ideas could explain what features peculiar to this engine were brought into the Austin 7.
Graham.

[Colin Morgan]

On page 9 of Jonathan Wood's Austin Seven 1999 book it says below a sectioned drawing of the engine: 

"The 7hp FN motorcycle engine that provided Edge with inspiration for the lower half of the Seven's power unit.  This 52 x 88 mm 748 CC T-head four was introduced in 1914 and reappeared in 1919.  The crankcase was aluminium, and Seven owners will recognise the splash-lubricated two-roller-bearing crankshaft."

Stanley Edge said that he gained some confidence from this engine that his crank design would be okay in the Seven engine.

[Graham Barker]

Hi Colin,
Thanks for the reply. Now I understand. I guess that Austin didn't have any "in-house" data for assessing crank strength of such a small engine when you think of the size of all the preceding Austin designs. Calculating the strength and fatigue resistance of a complex shape such as a crankshaft would be difficult without the use of computers. So being able to crib from a proven design would save a lot of trial and error.
Graham.