I plan on buying a rebuilt 13BT US motor. Can you guys give me good numbers for the 13BT? And the guy is gonna use a piston compression tester, so would the compression ratio still read the same or no? If no, how much would it read.

 

Good question, I am interested in seeing the answer, sorry I can't be of anymore help.

 

Leading plugs in, trailing plugs out.
If the engine has been sitting for a while, spray some WD40 in the trailing holes on all rotor faces to free up any stuck seals & build compression.
Install the testor & crank the engine.
Here is the tricky part.
Open the bleed valve on the testor just enough to see the needle bounce up & down between each face.
Observe the sets of three pressure peaks.
I have read that 120's are possible in a perfect engine.
100's - good
90's - OK
80's - about worn out

When I broke an apex seal I got 85-50-50
The J-spec is showing 95's

 

Hey Sure Shot what's the difference if you pull out the little spring thingy on the tester or hold it open? do you get different readings?