frankvan

WRT not tight enough retaining nut, I can't speak of experience with the Porsche but with my Alfa it did happen. Luckily it was on the front (ie easy access) bank - exhaust valve and it was a very loud ticking! ( I mean loud! ). ACtually what happened was that the retaining nut was so loose that the adjustment screw worked it's way right out of the rocker arm and was just sitting on top of the head in the oil. In essence the valve wouldn't open at all and the cam just slapped against the rocker arm (no engine damage thankfully) BTW, never did go back to that mechanic (plus he overcharged)

greenjt

I was waiting for an answer to that myself... I'm no expert but did do my first adjustment last january. It would seem that there could be a situation where the nut was not snugged down enough and it could come loose. My biggest challenge was tightening the nuts enough while maintaining the correct gap - took some practice.

Wachuko

Yes... same here. Even after going over the adjustment twice I always have my doubts if I did them correctly...

I am getting ready to change the oil in the car... so I think I will open it up again to validate they are adjusted correctly...

dfinnegan

So, why do the valves get out of adjustment then? Is it wear? Is it that the adjusting screws just backout over time with use even though the lock nuts are tightened to spec?

Just curious,
Dave

frankvan

I haven't done an adjustment myself on the Porsche (yet) but have done a couple on the Alfa (after that scary experience of someone else operating on my Italian child). To be honest, 5 out of 6 exhaust valves are always in spec and there never is any deviation on the intake valves (which is good because those ones require shims to adjust!) so minimal adjustment is usually required.

springer3

I don't think the stud/jamnut can change if they are tight enough. I have never seen one loosen, but I have seen mechanics over-tighten and damage the threads.

Wear and erosion at the valve/seat contact causes the lash to get closer. Wear in the rocker or valve tip causes the lash to increase. Any big change is cause for alarm. Every time I have done mine, including an early 911, I have found none to fewer than half needing adjustment. I have made adjustments in both directions. It is easier to check with a dial indicator, where you get an exact reading. If a valve needs adjustment, I find the feeler gage is the way to go (except to check afterwards with a dial to confirm it is spot-on).

dfinnegan

Thanks, Paul.

marcandkimmie

Thank you guys for your answers.