Valve problem
 

I have had a dead cylinder (#5) since I've re-installed my engine last month. The cylinder drops out when the engine gets to operating temperature I thought I was having an ignition problem problem but I've replaced everything ignition related for cylinder #5.

Tonight I pulled the rocker covers on the passenger side to check the physical side of things. I didn't see anything out of order for #5, everything is new anyway, this engine maybe has 2500 miles on it, probably less.

Next I set #5 to TDC and attached my leak tester to the cylinder. I pressurized the cylinder and heard air escaping right away from the lower rocker area. A lot of air in fact. So I loosened the adjuster nut on the valve and nothing changed. I then backed the adjuster off and nothing changed.

This is where it gets weird, I adjusted the valve down (tighter) and after the adjuster contacted the valve it was about 1 turn of the screwdriver and the leak stopped all together.

What I'm trying to figure out now is whats wrong? Why would tightening the valve cause the valve to close? Why was it stuck open?

Piece of carbon might have fallen between the valve and seat. Repeat the air pressure test to see if that might have been it.

Tightening the elephant foot puts pressure on the valve. Is there a chance this pressure could be sealing a loose head/cylinder?

I am thinking along the same line as Bob.

I am no expert, but I do check the torque on all the heads within the first 300 miles driven on a rebuilt engine. Just my two cents.

Good luck.

I did check the head studs at the first valve adjust which was shortly after the engine was rebuilt. I'll check them again tomorrow and report back.