Dual Dells car shakes just off idle

Video clip here

Is there something wrong with the carbs, are they out of balance or is it something else?

Blocked idle or water in fuel?

Have they evaer worked??

It is unlikey they go out of tune by themselves

Any diagnostics that you could recommend to narrow it down?

It idles smooth, but just when I'm giving it a little to engage the clutch it starts to wiggle at the back. Mid range and top end pulls well and smooth.

In the video you can see a couple of times the rear wiggles side to side.

Have you got the carbs sync'd properly, and are the butterflies opening at exactly the same time and rate ???

Anything out of whack there would show up more at low throttle openings, which is I think what you're describing...

Engine off, throttle cable disconnected, return springs unhooked, your linkage should work smooth and accurate - think swiss clock.

Ah yes, I took the linkage off to replace a perished fuel line not too long ago. That may have done it.

Yup - pretty likely.

Ideally you want the butterflies on the two carbs to open at EXACTLY the same time and rate... if they don't you've effectively got one side of the engine making more power than the other, hence the shake.

When you've got the carbs sync'd and the linkage right, you'll be amazed how much difference it makes.