Hiya- Going through the valves on my 996SPS, here is what I have so far (on T1 cams). Was shooting for 0.1mm all around, except for 0.15mm on the exhaust openers. All are on old half-rings except the right exhaust closer. Is this close enough, or is the horizontal cylinder too tight ? I've heard of people running very tight closers, and it there is no drag at all when I spin the cams (and I measured at multiple points)... But when it's all hot and spinning, I don't know what might change. Any advice much appreciated. Thanks ! Vertical Cylinder: Left Intake Opener: .13mm Left Intake Closer: .12mm Right Intake Opener: .13mm Right Intake Closer: .10mm Left Exhaust Opener: .13mm Left Exhaust Closer: .12mm Right Exhaust Opener: .15mm Right Exhaust Closer: .13mm Horizontal Cylinder: Left Intake Opener: .09 mm (too tight?) Left Intake Closer: .06 mm Right Intake Opener: .10 mm Right Intake Closer: .05mm Left Exhaust Opener: 0.13mm Left Exhaust Closer: .10mm Right Exhaust Opener: .10mm (too tight?) Right Exhaust Closer: .04 mm (new half-rings)
My opinion only but have a look at the attached. It's American so .004" = 0.1mm and .006" = 0.15mm Vertical Cylinder: Left Intake Opener: .13mm OK Left Intake Closer: .12mm OK Right Intake Opener: .13mm OK Right Intake Closer: .10mm Perfect Left Exhaust Opener: .13mm OK Left Exhaust Closer: .12mm OK Right Exhaust Opener: .15mm Perfect Right Exhaust Closer: .13mm OK Horizontal Cylinder: Left Intake Opener: .09 mm (too tight?) No, OK I THINK Left Intake Closer: .06 mm a tad tight Right Intake Opener: .10 mm Perfect Right Intake Closer: .05mm a bit tight Left Exhaust Opener: 0.13mm OK Left Exhaust Closer: .10mm Perfect Right Exhaust Opener: .10mm (too tight?) yep - a tad tight Right Exhaust Closer: .04 mm (new half-rings) check for binding should open a little on use when collets bed - need to check after 1000km - messy job opening that side as it drips oil in your face
IMO mostly OK, I aim for 0.10 - 0.12 openers and 0.05 closers (definitely less than 0.10 and as tight as possible with no drag for the closers) however I don't think 0.15 is excessively loose for an opener, especially an exhaust. So on that basis, I would open up the left intake opener and tighten up any closers with 0.10 or more - those highlighted in red in the quote. Fitting new half-rings may tighten everything? My recommendation is to fit MBP retainer/collets. I fitted them to my 916 many years ago and rarely need to adjust anything.
Wound up with the following: Intake openers (all): 0.10mm Exhaust openers (all): 0.15mm All closers: 0.05mm (on was 0.08mm) thanks!
