valve guide interference fit

[etsjw]

Does anyone have any guidance regarding the interference fit between the valve guide OD and the ID of the guide hole in the head casting?
In other words if the head casting guide hole is xxx mm how much larger should the guide OD be?
Thanks

[LaceyDucati]

I work on 0.03 to 0.035mm, any more will push the guide off centre (more) and stretch the hole. any less than 0.025mm and it's likely to come loose. Regards Nigel

[etsjw]

Thanks, Nigel
John