Engine running on and juddering after switch off

[tamson]

My 2ltr CU engine has developed an annoying habit of juddering quite violently when I turn the ignition off. It doesnt do it every time but mainly if its been running a good while. Only thing I can think is I recently replaced the bypass air cut off valve, but it was with a Brosol one intended for a beetle. Not sure if this would make a difference? The engine was only rebuilt 3000 miles ago by the way. Thanks

[john1]

I could be wrong but I would check the timming.

[Footprint]

Check timing as suggested, but I'd imagine the solenoid valve from a beetle doesn't close off the idle airway fully - which would lead to the sort of problem you've encountered.

[tamson]

Cool I had a feeling that was the problem. Ill check the timing at the weekend. Is it possible for the timing to knock its self out of adjustment?

[CovKid]

Footprint has it.