Conrod length

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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mdt-son
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Conrod length

Post by mdt-son »

Hi all,

I am trying to compel a complete list of engine data for the 1960-on h/w singles, similar to what was published in the Osborn book.
I would like to know the length (center big end to center small end) of 010312 Conrod, 350/500 STD, 1950-63.
I am sure someone has this conrod in his drawer. Help would be appreciated.

Regards,

Knut Sonsteby
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Duncan
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Re: Conrod length

Post by Duncan »

According to this article: http://archives.jampot.dk/technical/Spe ... _1982).pdf
The up to 47 Conrod was 7 3/8" and the 47 on was 1/2" shorter (6 7/8").
mdt-son
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Re: Conrod length

Post by mdt-son »

Thanks Duncan,

I read this article too and hoped someone would confirm by measuring a conrod. If 6-7/8" is correct, what is the 500CS conrod length (022397) ?
I have one here which was advertised as being for the 500CS - not so sure anymore. Its length is exactly 6-7/8". If they had the same length, there must be some other differences.

-Knut
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ajscomboman
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Re: Conrod length

Post by ajscomboman »

Hello Knut

The CS rod is 6 7/8".
SPRIDDLER
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Re: Conrod length

Post by SPRIDDLER »

mdt-son wrote:......... there must be some other differences.
Can you clarify what you mean by differences?

Regardless of the conrod's length it will not alter the stroke of the engine. When the conrod length of the touring 500 was reduced by 1/2" in '47 the gudgeon pin was also lowered by 1/2" to maintain the same comp ratio.
I'm not especially familiar with the details of the CS engine's innards but if you are referring to the difference being that the CS is more 'powerful' than the touring 500 this is due in part to the higher compression of 8.7 of the CS versus 7.3 for the Touring 500's which is obtained by piston design. I think there were also differences in the valve cams' profile. Possibly also valve size and carb used. Reference to the specifications in the workshop manuals would confirm, (plus a contribution to this thread from someone who actually knows ;) )
'There is a tide in the affairs of men
Which taken at the flood............'
mdt-son
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Re: Conrod length

Post by mdt-son »

G80Cs conrods were forged, conrods for touring singles were cast. From 1964 on all conrods fitted to the singles were of the forged type.

- Knut
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