Check your cam timing after setting initially! Don't be like me

[stownsen914]

Phunt - call Webcam. They should have the lift at TDC number to give you, as this is the standard way to set cam timing on 911s. And yes, you are correct to not use the stock 3.2 cam timing numbers for this aftermarket cam. That would definitely be incorrect. A more aggressive cam like this one may have TDC lift numbers in the 3-5 mm range to set timing.

You can do it with a degree wheel and a dial indicator on your valve to measure lift too if you wish. The .050" measurement just means you're measuring timing from the time the valve has just started opening, at .050", until it's .050" from being closed again. Hence the .050" duration numbers are a little less than the full duration numbers. And yeah you normally check valve timing like this at zero lash, as lash would just introduce error.

[Tippy]

phunt - I believe lash increases at operating temp. I could be wrong, but I know this topic has been discussed on here.

[Tippy]

Originally Posted by JoeMag

...regarding truly timing the cam with degree wheel versus over-lap. I'd propose it depends on what level of performance or accuracy you're looking for. Doing over-lap you're timing to a single point and really do not know if the cam is really made to "specification" (lift and lobe separation).

In various stages of my race engine development I've purchased two cams in the last ~3-4 yrs. Both were not to spec, at least in my mind using a degree wheel to time them. Earlier one was supposed to be 106 lobe angle. Left was fine, and right was pretty far off at 111. Most recent is being rechecked by someone else.

Great data point

[Tippy]

Originally Posted by stownsen914

I'll echo JoeMag's experience in having a pair of matched cams with different lobe centers. I timed them using the factory method (#1 and 4 intake lift at TDC), and then being curious, checked the exhaust lift specs, and then checked everything with a degree wheel. After initially being confused why I was getting different results left to right, I realized one cam's lobe separation was off by several degrees. I either advanced or retarded one side by a couple degrees (I forget which) to "split the difference" so to speak when I set the timing.

Great, now I want to check it all again. HAHA. That is crazy though

[phunt]

I have spoken with webcam and these cams need to be set via lobe center. There is no overlap data. It is still easy to do. And as far as I am concerned it is more accurate.
Valve lash on these solid style lifters absolutely gets smaller or tighter as the engine gets hot. If the lash grew got looser went from .004 to say .0075 the valves would clatter like crazy be very loud and change the cam timing. Reduce duration, lift and just kill power plus beat themselves to death. Expansion is why we set lash when everything grows the lash decreases gets tighter Should go from .004 to like .0005 or less just not negative. Then nice and smooth and quiet and on time.
I was hoping someone had a degree wheel for Porsche or good tell me how they did it. I had to suck it up and by the Stomski digital one.
These are simple engines so I believe Porsche uses the overlap method for ease and quickness
Just look at SC cams that the same grind depends on which engine it is in for overlap specs from .5-.7 on one all the way to 1.5-1.7 on another. Same cam. ??

[PeteKz]

Yes, the SC cams are the same from the 3.0 SC though the 3.2 Carreras (according to Bruce Anderson in his 911 Performance Handbook). Porsche specified a number of different cam timing lifts over those years, and they eventually settled in the middle of that range, about 1.1mm

[panama911]

Originally Posted by phunt

Valve lash on these solid style lifters absolutely gets smaller or tighter as the engine gets hot. If the lash grew got looser went from .004 to say .0075 the valves would clatter like crazy be very loud and change the cam timing. Reduce duration, lift and just kill power plus beat themselves to death. Expansion is why we set lash when everything grows the lash decreases gets tighter Should go from .004 to like .0005 or less just not negative. Then nice and smooth and quiet and on time.

...No, it doesn't; the opposite is true. The aluminum cam carrier and heads on our engines grow more with heat than the steel valve stems do.

Just look at SC cams that the same grind depends on which engine it is in for overlap specs from .5-.7 on one all the way to 1.5-1.7 on another. Same cam. ??

This is a way to spec different timing in different engines: the first more retarded, the latter more advanced.

[STYZ993911]

Thanks for sharing.

[phunt]

Panama
There is no way that the lash gets wider. No way.
Sure different metals expand at different rates. Thats why we set lash.
If as you say the lash or space between the lifter and the stem grows or gets wider you would hear the valves clatter. I don’t hear that. Have you ever heard an engine run with loose vale lash? It is pretty loud. In fact the engine seams to run smoother as it warms up.
One sure way check the lash when the engine is hot.
If you know someone with a test stand it would be easy.
I will stand be my statement. No way the valve lash gets bigger wider looser when it gets hot. No way

[phunt]

Well I am wrong. Lash will increase with temperature. As engine gets hot the lash grows gets wider gets looser. ��