Ignition question

[breng]

I adjusted the timing in my SD1 VDP EFi - it was struggling to turn over, as if the timing was too far advanced.

I set the timing to 8 deg. BTDC but noticed that the mark on the pulley kept moving - i noticed the engine running differently when this happened.

Dodgy centrifugal advance or a bad no 1 lead?

Thoughts please.

[sowen]

Sloppy cam chain letting the dizzy wander? Worn distributor shaft? Loose vacuum advance?

[ChasR]

What Sowen said.

You could try another dizzy, but chain wear has be known to cause timing scatter on Rover V8s as well. I guess you could rule out the vacuum advance being iffy by disconnecting it.

[breng]

Chain set is brand new - an all steel item.

If it was that, the moving timing mark would not be intermittent - it always moved back to the pointer, which makes me think it is a dizzy broblem.

[breng]

I had a suck on the pipe that attaches to the vacuum unit - i could see the mechanism moving.

[sowen]

Is there any 'free' play in the advance mechanism, before the vacuum and centrifugal weights give resistance?

[taurus]

Or play in the dizzy shaft? That will alter the points gap thus throwing the timing around.

[bortaf]

did you set the timming with the vacume advance disconnected ?
IME it's usually a worn dizzy bearing making the timming scatter but you never know .