(24 hp engine on a Cub Cadet mower. V-twin. 2004 vintage 274 hours. Left side of engine (looking from the carburetor) had bent push rods. On the intake valve the valve guide got displaced and locked up the rocker arm. Decided to buy 2 new heads from Amazon due to hours on engine. Installed both heads, proper torque and valve clearance.)
Heads included valves, springs etc. all assembled.
Did the leak down test at 15 psi. Both cylinders leak an equal 25% which, on my gauge, means "low leakage".
If I depress the valve springs with my fingers (during the test) I obviously get great leakage at that valve.
Curious thing: I upped the pressure to about 80 psi and the push rod (all 4 push rods are brand new) on the exhaust valve came out from under the rocker arm and fell to the ground.
Maybe I should stop mindf...ing wiht this engine and simply try to start it. There was a respondent on this group that thought 0 compression is valid.
Thank you all. Now I have a new tool (Lead Down Tester)
Ivan Vegvary