Trying to find the cause of a dead cylinder. New plug, wire dizzy, coil, cap. Have spark at plug. Pyrometer shows no 2 exhaust header pipe at 200 degrees after a warmup. All others are at 350/400. Pull the plug wire off and no change in engine. what's weird is I have 160 pounds of compression and zero leak down (zero gap rings).
It seems it has to be a valve. lifter, spring problem but before I pull off the valve cover (pain in butt) I'm trying to understand what could cause the problem.

Broken spring. weak spring etc? Just kind of laid down when I came to a stop.

 

Is it making any strange noises ?

 

No noise I can hear. It's a roller cam so probably not a bad lobe. Stainless valves, stelite seats and bronze guides, roller rockers. My working theory is worn out or broken springs. They were used in the last build so they have some miles on them and are a little light for the cam. It's dead right off idle though, guess I'll have to pull those two and test them.

thanks for any ideas.

 

I think you have the answer when your "working theory" hit upon worn out/broken valve springs.

 

Broken spring! Guess it's time to find a replacement set. Probably needs more pressure anyway.

 

How is the valve guide ?

 

Should be good. Low miles on the buildup except for the springs. Need to get a spring micrometer to spec new springs. Has hydraulic roller cam and lifters.