Quote Originally Posted by JohnL View Post
What difference is there between "K20 spec" clearance and stock?

My understanding is that you want the minimum cold set valve clearance possible that allows some minimal clearance of the cam lobe base circle when all is at operating temp (with hotter and elongated valves etc...). The smaller the clearance the higher the valve lift and the longer the duration (ever so slightly for both), which should improve breathing just a gnat's whisker.

If this is what the 'K20 spec' is (i.e. a tighter clearance) then it should help power to an infintesimal degree so long as the base circle is not touching the follower. But if the K20 spec is a larger clearance that is not required to provide adequate clearance then it may infintesimally hurt power.
the K20 spec is tighter... and yes your right, thatll mean slightly more lift and duration on the cams... which should mean slightly more power...

the main problem you might face with the tighter settings is that the valve doesnt seat properly with the weaker K24 springs, equalling loss in power

Correction - K20 and AUDM K24A3 spec are the same... lol i was looking at the USDM K24A3 spec...

K20 spec:
Intake: 0.21-0.25 mm
Exhaust: 0.25-0.29 mm

K24 spec:
Intake: 0.21-0.25 mm
Exhaust: 0.25-0.29 mm