valve timing for Festiniog Linda

[Roger Davies 3Participant @rogerdavies3]

Can anyone verify how to set the eccentrics for accurate valve timing on this loco?

There is a 6 degree angle between cylinders and valve gear and a rocking lever.. So should the eccentrics be set at : forward gear, 84 degrees behind crank, reverse, 96 degrees ahead of crank.

[Roger Davies 3Participant @rogerdavies3]

setting of eccentrics

[Neil WyattModerator @neilwyatt]

Hello Roger,

Welcome to the forum.

At a guess, no. I'm assuming its Stephenson's gear, in which case the eccentrics need to be advanced slightly to provide lead as well as making an allowance for the angle between cylinders and valves.

I'm sure an expert will be along soon, but I expect they will recommend setting the eccentrics so the valves are open just by a crack (traditionally the width of a tram ticket) at TDC,.

Neil

[Ian S CParticipant @iansc]

Tram ticket? I remember two sorts of tickets, the one you are thinking of Neil was similar to news print, the other was about 1/16" thick card, both about 2" x 1". sorry, a bit OT.

Ian S C

[julian atkinsParticipant @julianatkins58923]

hi roger,

LINDA has stephensons gear indirect drive with rocker arms, and launch links and slide valves.

you are correct in assuming that the eccentric settings are shifted around by the amount of inclination of the gear to the cylinder centre line.

with launch links the angle of advance ought to be more than 6 degrees – though your reference to 6 degrees is the above inclination and not the angle of advance as commented by Neil.

my own version of LINDA is in 3.5"g and the gear was worked out by me using Don Ashton's excellent booklet many years ago.

cheers,

julian

[julian atkinsParticipant @julianatkins58923]

hi roger,

LINDA has stephensons gear indirect drive with rocker arms, and launch links and slide valves.

you are correct in assuming that the eccentric settings are shifted around by the amount of inclination of the gear to the cylinder centre line.

with launch links the angle of advance ought to be more than 6 degrees – though your reference to 6 degrees is the above inclination and not the angle of advance as commented by Neil.

my own version of LINDA is in 3.5"g and the gear was worked out by me using Don Ashton's excellent booklet many years ago.

cheers,

julian

[Roger Davies 3Participant @rogerdavies3]

Thanks. Not sure why it should be more than the 6 degrees though

[julian atkinsParticipant @julianatkins58923]

hi roger

ive sent you a pm

cheers,

julian

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