Quote:
Originally Posted by jdd
According to the Dec 2007 copy of TIS I have, the oversize valves are listed as available for the M62 (4.4 and 4.6). The standard stem diameter is listed as 6.0mm with oversizes of 6.1 and 6.2 available.
The TIS doesn’t mention anything about oversize stems available for the N62 (4.4 or 4.8) but since there are aftermarket valve guides available for the N62, I would assume you could also get aftermarket oversize valves as well.
Depending on what wears, which I assume most of the wear is in the guide and not the valve stem, if this were my car that I intended to keep, I would be looking at getting after market valve guides fitted.
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Thank you jdd for the information.
In the meantime, I talked to a friend machinist, and asked him about re-boring the head + bigger valves vs re-boring + installing the new guides, and the option of installing the new guides is the best one, especially, like you said, when someone plans on keeping the car for a long time (servicable in the future).
The guides are cheap, its the labour, as usual, that is the big chunk of the bill. The stock valves shouldn't wear (steel), it's the head (aluminum) that should wear, so, new guides with the original ID should work with the stock valves.