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3.0 noise Identification

My hearing is not what it used to be, so I'll take Chris's word at it, and if this is detonating, you'll want to correct this ASAP.
Causes:
Lean fuel/air mixture and/or poor fuel quality.
Early ignition source.... I.E., too much spark advance and too early.
Poorly designed combustion chamber.

The chambers on this engine are OK.
Doubt that anyone has played with your high speed fuel metering.
Most likely candidate is ignition timing or poor fuel quality.

I'd be looking at my ignition timing throughout the RPM range and compare this to the OME specs.
We're not talking Base or Initial advance, we're talking progressive and full in advance.

Detonation can cause many forms of piston damage.
Take a look here.... you'll definitely want to avoid this.
http://www.google.com/search?tbm=is...10698l17l17l0l0l0l0l140l1311l16j1l17l0.frgbld.
 
If the clicking I could hear and it was very random not a repeatable sound like a lifter or rod or such.

Most likely the exhaust flapper lost its rubber outer coating and it clinking against the exhaust tube........

With the wind over shadowing the engine it is very hard to hear specific sounds.......

Also

WHat rpms were you running? Just want to know.
Did the motor over heat recently?
 
One observation is constant blow by thru the hose going to the flame arrestor may be a sign of bad things to come.....some maybe but excessive no.

The fact that you had a bad valve, was the head rebiult?
It may have happened again....maybe a bad valve.

It will be very hard for anyone here just listening to a running engine with all the wind noise to make a real diagnosis. YOU need someone with some test tools and knowledge to help pin point your issue.


Just my thoughts...
 
Docksidemarineservices said:
Sounds like detonation.

That engine sounds like it is eating itself. When they start to sound like a lawnmower, it won't be long.
Click to expand...


And yours sounds like a lawn mower!

Every pop is detonation and a back fire into the exhaust. You can hear the rpm's drop out at every pop. Almost like your hanging and exhaust valve at high rpm. Pull the valve cover and remove the rocker arms, look for the valve that is sitting higher than the rest. Tap them all with a small mallet to make sure they are closed . Bet you tuliped another valve.
 
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I would do this first before you do anything else, disconnect the wire from the tach at the ignition coil and rerun the boat and see if your problem still exists. In the video looks like the tach dropped before the noise.
 
Could it be your distributor ticking? I know I can here mine at low rpms but I guess it probably would happen at higher rpms due to the higher frequency. Listen to it when it's idling and see if you can really hone in on where the noise is coming from.
 
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