Valve to piston clearance mod

[kium]

Hi guys,
I really need your help here.

Trying to make the best out of my lock down I'm putting all my hours into finishing my 2.2t engine rebuild I started last summer and but never seemed to have time available for it. You see wifey, now it's a great thing to have a Porsche in bits around... LOL

I'm following Wayne's book and all your posts and I'm enjoying the rebuild, until yesterday when I checked the valve-to-piston clearance.

#1 cylinder ok, at least 0.5mm over the minimun required in Wayne's book (1.5mm intake, 2.0 exaust)

#4 cylinder, intake ok but exaust was just under 2 turns (I recon 1.9mm)

I was wondering if a change in the cam timing would give me that extra clearance.
For the 2.2t Wayne recomends an overlap between 2.2-2.7mm, being 2.5 the target setting, which I actually managed to get spot-on on both cams.

What if I alter my timing? always in between the recomended values, let's say 2.2 (or maybe 2.7, I really don't know which way would be better if it worked). Would I be able to get that extra 0.1mm recomended?

Should I not worry for such a small difference? (silly question, I know)

Thanks to all and take care.

[r lane]

Those clearances are for high rpm and a possible over rev. Unless you are tracking it, I wouldn't worry about ,1mm. also I doubt if you would notice drivability issues from one end of the cam spec to the other. Bob

[kium]

Thanks Bob for your quick reply.
My intention is also to put the MSD ignition which incorporates also a rev limiter, so that will give me some extra peace of mind.
Cheers

[stownsen914]

I also would not be concerned about .1mm less clearance.

[Eagledriver]

Porsche only requires .8mm clearance. You will be fine.

—Andy

[Richey]

Set the cam timing to the high end of the range , the exhaust valve will be closing more and there will be more clearance . I believe this is the info you were asking for .

[kium]

Wow!! Lots of good information.
Thank you stownsen914, Eagledriver and Richey.