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Collection, Preservation and Display of Old Lawn Mowers

BSA F12 Sloper - thickness of Valve Chest cover Gasket?

I have just taken delivery of a Ransomes 18" Marquis Mk5, Serial Number EH1310, which has a BSA / Norton Villiers F12 Sloper engine, Number RS119B 3028 K.

Firstly any ideas as to the Year of Manufacture - 1970?

Secondly I have noticed an oil leak from the Valve Chest Cover, and I presume (before draining  the oil and removing the cover) that the gasket is either split or not present.  What is the approximate thickness of the gasket, so that I can cut another one.  I have either card or cork gasket material...

Many thanks - Mark


wristpin Fri, 27/04/2018

Valve chest gasket. It’s just paper and less than postcard thickness but often the metal cover is warped / distorted. It’s worth the time putting  a sheet of fine emery cloth on a flat surface and rubbing the cover over it to detect and remove high spots. I always put a smear of heavy grease on both metal surfaces.

Age. No real idea but guessing that it could be earlier. Paul at Meetens is the man to ask.

Mr. E Sat, 28/04/2018

Made a copy from Gasket paper -  and thorough cleaned by mating surfaces, using 1200 grit and a Swiss file.  Bingo - no oil leak!  The original gasket had partially disintegrated, causing an oil leak directly onto the exhaust.  Smoked a bit for several minutes, until the oil residue had burnt off the exhaust!