Help! Valve to piston clearance mod
 

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.

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

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

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

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

—Andy

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 .

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