I was yesterday eveneing visting at my buddy's garage after he had found some metal particles from used oil when he had changed the motor oil. Found out that problem was caused by broken valve guides and pulled the heads up from the engine.

Find enclosed a picture from broken guides. There was 4 broken guides. Asked from my buddy had he checked the valve guide clearances before installation? Answer was no.

Has anyone else had similar problems with these heads and have you used some standard replacement guides or specially machined to fit the 440Source heads?