1986 911 Carrera 3.2 leakdown and compression numbers
 

What numbers should I be looking for to determine a healthy engine during a PPI?
Thanks in advance.

Exact compression pressures are hard to predict. Even pressures within a small range is what you look for. A proper test is done hot, throttle locked wide open, battery charger on and cranked until no more pressure increase.

Leakdown should be less than 10% at most. 5% would be real nice. Anything over 10% they should be listening to the intake, exhaust or oil fill to see if they can hear the air leakage.

These are just guideline and my .002

Good luck!

911 cyl leakdown
 

Wayne sez: SmileWavy

A newly rebuilt engine should have leak-down percentages of around 3-5%. An engine in good running condition should show 10% or less. Numbers around 20% indicate some wear of the engine, but are still adequate for good engine operation. Leakage numbers of around 30% indicate that there are problems brewing,
Pelican Technical Article: Time to Rebuild? - Part II

buy the book - it will save ya a lot of grief :)

For your reference, here's what I got on my 1985 911 last October with 67,353 miles. It runs great including at a DE, doesn't leak any oil, and starts right up.

compression:
#1- 175 psi
#2- 180
#3- 180
#4- 177
#5- 180
#6- 180

leak down test:
#1- 2.2%
#2- 0.0
#3- 2.2
#4- 3.3
#5- 1.1
#6- 2.2