That tell tale puff of blue smoke when you first start is an indicator of worn guides or seals. Valve guides should be replaced with every valve job. Sold individually these are the original quality Cooper S guides for use in any head that is leaded petrol or uses chrome stemmed valves.
Also suitable for any of our plasma or heat treated competition valves when using unleaded petrol.
Not for Turbo exhaust valves as they have a 8mm internal diameter.