burned exhaust valves 3.0 1989

[Mike Spijkerman]

I had a running problem with my 3.0 omc 1989. I took the head off and i noticed that all the exhaust valves are burned. So much that the are bend . Which resulted in a crack in the cilinderhead. Now is my question what the cause could be. I ordered a new head. not that i burn the new valves. I live in Europe maybe we use a different type of unleaded fuel? 95 octane we have overhere.

M Spijkerman

 

[Boobie]

What's the ignition timing set at ??

 

[johnnygjr]

Possibly running very lean also,engine running hotter than normal,from timing being off causing detonation!!

 

[kimcrwbr1]

That has the rochester carb be sure and give it a good rebuild and go through the distributor as well. Make sure the flyweights and springs are in good condition just put a couple drops of engine oil on the pivot points and on the shaft. Check the timing chain also while you have it apart.

 

[kimcrwbr1]

I just checked it has timing gears they virtually never go bad focus on carb and distributor advance and adjust the points using a dwell meter for any marine application.

 

[Mike Spijkerman]

What's the ignition timing set at ??

4 degrees BTC

 

[Mike Spijkerman]

I recently rebuild the carb. en i use a elctronic upgrade to get rid of the points.

 

[kimcrwbr1]

You still need to check the mechanical advance is working properly. Detonation is more than likely a big part of the problem plus the 95 octane fuel. Is that the pertronix/hot spark ignition module you replaced the points with?

 

[Mike Spijkerman]

You still need to check the mechanical advance is working properly. Detonation is more than likely a big part of the problem plus the 95 octane fuel. Is that the pertronix/hot spark ignition module you replaced the points with?

petronix, i can't find the ignition setting with my 95 octane