89 omc 5.7 dead cylinder

[Ppichey]

Hi,I have an 89 omc 5.7 that I rebuilt last winter, I have been troubleshooting the motor all summer and almost have it perfect,took it to a local mechanic to have the valves lashed and when it came back I have a huge miss,pulled all the plugs and cylinder 8 plug has a missing electrode,took it back to the mechanic and he said the lash is right must be something else,guy told me he had pushed the motor to 4600 rpm on the hose!!!i had 4 valves that were to tight and he adjusted them but now I have no compression in 1 cylinder,figure I need to pull the head off,what am I looking for?bent valve?hole in piston,just ticks me off because I took it to a “professional “to haVe that done,That’s for any advice in advance

 

[alldodge]

Sorry to hear about your issue, and there is so many they are listed as "pros" but the only part of pro is the they are a pro at screwing things up

Running any marine motor above 1800 rpm on a hose is bad news, and a pro would know that

Back off all the rockers and let them clatter some. This will allow the oil to pump back up in them

Bring a cylinder around to TDC and then while rotating the push rod in your fingers back n forth and up and down. Tighten the rocker a little bit at a time until the up and down movement stops. When up and down movement stops there may still be back n forth but this is irrelevent, its the up/down your feeling for.

Once all up and down stops, rotate one more complete turn and then it is set.

Rotate motor and get another cylinder

 

[Ppichey]

Ok will do that,kinda worried about where that spark plug electrode went to,havent seen it anywhere as of yet.thank you for the advice!