Interesting compression vs leakdown numbers - different story told
 

I've just dropped and partially stripped my 3.2 motor to cure oil leaks, which turned out to originate from a barely attached breather hose, and high oil consumption/occasional smoke which I presumed to be guides. My thread is here http://forums.pelicanparts.com/porsche-911-technical-forum/772047-1st-drop-top-end-observations-questions.html

Thought I'd post some numbers you all might find interesting.

Compression test was done with the motor in the car, all plugs out, WOT, good optima yellowtop, at least 12 cranks. Engine was just slightly too hot to touch.

1: 175
2:187.5
3:190
4:175
5:180
6:180

Leakdown was done @ 50psi, brand new tester from amazon (Amazon.com: OTC 5609 Cylinder Leakage Tester Kit: Automotive) engine was on an ATV jack and therefore cold (well, 70 degrees F).

1: 12%
2: 1%
3: 20%
4: 25%
5: 2%
6: 70%!!!

I listened very closely to where the air was escaping from. The intake runners, intake valve covers and rear breather cap were removed. I sprayed WD-40 on each intake valve as a tell for leaking air. The interesting thing is that all cylinders had roughly the same leakage around the SEAT of the intake valve. There very well may have been leakage elsewhere (seal, guide etc) but the leakage around the seat makes it hard to pinpoint any other leakage. In addition, almost all cylinders, even those with nearly no leakage, had audible hissing from the breather, which would indicate rings. what is so confusing is that both the spitting from the valves and the hissing from the breather were approximately the same intensity for all cylinders.

I double checked that the intake valve stem was loose and chattering on the rocker before each test and did each cylinder twice.

When my engine yoke arrives I'll be very curious to see what the cause of these numbers is, but I would like any opinions you have on how I could get such uniform and decent compression numbers with such wildly varied leakdown numbers.

You cannot get 180 psi compression with a 70% leak down. The possible reason is when the engine is being removed, pieces of carbon has fallen down and blocked the valves from being closed properly.