absolutely sure the noise comes from #2 and #4 cylinders.
removing/installing spark plugs in #1 and #3 doesn't change the noise.
removing/installing spark plugs in #2 and #4 makes the noise disappear/reappear.
Ok, I figure I have a leak somewhere.
It can be at 3 places:
1)exhaust valve 2)intake valve 3)between head and cylinderfor a test, I decide to put some oil into cylinder #4. Put the spark plug back in. Adjust #4 exhaust valve completely out (so exhaust valve does not get opened). This creates a situation where the #4 cylinder will a)intake b)compress c)not exhaust
I used a wrench on the alternator nut, cranked the engine until it locked up. cranked harder. completely locked up.
I was looking for a leak.. perhaps the oil was too thick to escape through whatever leak exists.
Ok, test failed to give me any good data.
rough adjust exhaust valve so it is opening again. crank the engine to let some of the oil out of cylinder. replaced spark plug....
no more noise from left side of engine!
ok, so either
1)oil still exists in "crack" that is leaking pressure 2)oil lubricated whatever spot was chirpingarghhh