Valve timing

[johnp]

How do i set the timing on a compound engine

[gondolier88]

Set the HP first- pre-entry at between 5-7deg. before TDC/BDC in 'ahead', aiming for as close to that as possible in 'astern'. Exhaust should be set by the lap of the valve if machined correctly. If possible, any tendency for the valve gear to give more steam entry at one end of the stroke than the other, make sure is used for the BDC as more cushioning is required (gravity!) to stop the downstroke, and more steam is required (gravity again!) to push it back- a little academic, but any error in the valve gear can be made to work to your advantage.

Then do exactly the same for the LP. If the crank is machined correctly and all clearances on the eccentrics are within tolerance then the HP exhaust will fill the LP receiver at the right point for the LP steam entry.

I'm assuming you have slide valves on both cylinders here!

Greg

[Akitene]

Good evening gondolier88,

Is this procedure the right one for a cross-compound or a tandem compound engine?

Best regards.

[gondolier88]

Cross compound- I've never timed a tandem before- although the same would apply to the HP, I'm unsure about LP settings.

Greg