Oversized Valve Stems

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Simple question for those with experience building cylinder heads: If you use valves which have oversized stems do you need to use a different type of retainer?


For example, I know that many valve springs come with the valve retainers, but they do not mention valve stem size. Does it matter?

Obviously the guides will need to be sized accordingly or the correct guides need to be installed.

[riceh8r]

ok, so you got and '87 325is, same as me. was a little confused by your question. m20 has 7mm valve stem, that does not change. guides do...13.05mm, 13.11 mm and 13.25mm (o.d.). all of these use the same valve guide seal. all of these guide a 7mm shaft. the valve diameter varies only from 36mm exhaust, to 42mm intake. if you have 8mm valve stems, they are for an m10. in either case, the 7mm and 8mm valve stems use the same valve keeper.

[structured]

I know that this thread is a bit old, but I want to post in order to clarify so that people searching wont get mislead.

ok, so you got and '87 325is, same as me. was a little confused by your question. m20 has 7mm valve stem, that does not change. guides do...13.05mm, 13.11 mm and 13.25mm (o.d.). all of these use the same valve guide seal. all of these guide a 7mm shaft. the valve diameter varies only from 36mm exhaust, to 42mm intake. if you have 8mm valve stems, they are for an m10. in either case, the 7mm and 8mm valve stems use the same valve keeper.

Thanks for the response. The last bit was helpful but I have to disagree about the valve stem diameter. BMW did make a valve with an oversized stem (+0.1mm). You can find the part number here: http://www.realoem.com/bmw/showparts...66&hg=11&fg=25

If the m10 (8mm) and m20 (7mm) valve stems use the same keeper, then the oversized m20 valve stems (7.1mm) should be fine with that keeper as well.