Hello!

Has anyone ever constructed an mechanical or electronic delay for syncing a strobe with the rear shutter on a Speed Graphic?

Any comments/advise would be much appreciated.

on some of them it would be easer to resyncing the shutter carten

No. And there's a reason why.

The only shutter speed at which the focal plane shutter uncovers all of the film at once is "T". At all other speeds only a portion of the film is exposed; the shutter slit travels down the gate.

Few photographers want to expose only part of the film.

The only way to use electronic flash with a Speed Graphic is drop shutter. Fire the shutter on T, fire the flash manually, close the shutter. This has to be done in the dark, otherwise ambient light will spoil the shot.

If you want to use electronic flash with a Graphic, you'll have to use a lens in or in front of a leaf shutter that has X sync.