Both, I'm pretty sure. You can definitely hear it with the hatch down, and I think you hear it out the exhaust in back of the boat. Kind of reminds me of the "crickets" you hear from some of the high HP drag cars at the starting line.

Big issue is that I don't remember hearing it last year. If it was something like the tips making the sound, I would have remembered it from then.

Wouldn't a lifter going away produce a lot of metal in the oil filter? We cut the filter open last year at the end of the season and there were not any significant debris.

Jim, they are AFR 265's, so whatever kind of guide and seal they run. They probably do have a bronze liner in them, and yes, inconel exhaust valves.

Pretty much gonna say it's the more aggressive cam chirping that you hear, and probably not an issue at all.... Or metal flappers in tips on exhaust... Mine has little birdys chirping also, same ans many buddy's boats with more cam in them... The drier the exhaust the more you will hear it, most boats with wetter exhaust it gets drowned out...

You typically only hear this on very high compression, big cam, well tuned exhaust race cars. Most EVeryone believes it's just some exhaust port / pipe noise. These camshafts open the exhaust very, very early.

You can also get simialr noise from exhaust leaks. Especially very small ones that aren't big enough to let out exhaust noise, but enough where air/exhaust forced thru it 'squeeks' instead of whistles.

Any baffle or etc falling apart can do this.

Air moving past/around objects can make noise. Chirps and sqeeks and whistles are the most common.

However, metal on metal can squeek / chirp too...obviously.

So...if your concerned, you need to diagnose on your issue. HArd for any of us to tell you what it is....we'll just have suggestions where too look.

if this is a brand new noise I would take the time to pull the intake manifold off and have a look I was convinced that my tripping was coming from outside the motor coupler may be a gimbal bearing but after pulling the intake it was obvious that I had a roller starting to go south.

Spark plugs all tight?

I was able to catch mine early enough that we were able to replace the cam lifters springs and rockers without doing any other damage. No metal in the oil either.

Mine at idle no issues... Is this what you hear?

http://www.youtube.com/attribution_link?a=yFLhHHqKOXs&u=/watch%3Fv%3DHrOnCf1AMt4%26feature%3Dem-share_video_user

I appreciate all the replies! I am going to have to investigate this a little more thoroughly. RT930turbo has me a bit spooked - I would hate to wipe out an expensive cam and lifters on something like this. I'm going to run it on the hose and get a good close look at it, maybe even take a little video, listen around with a stethoscope, etc. Probably run a quick compression check at the minimum. If still not satisfied I'll pull the intake and have a look.

Full Force, come to think of it I was having some impeller issues, so probably not as much water was exiting the exhaust. I had smoked an impeller last year on the hose (did not overheat), and put in an aftermarket one that is not building goo water pressure. I was running between 5 - 7 PSI even at 3000 RPM over the weekend. Oil temp stayed at around 190* and water temp was around 150*, so no harm done, but it should be a lot higher than that. At idle it was barely reading on the gauge, although I could still see water coming out the exhaust.

Force, it does sound a lot like that - but I can hear it with the hatch down, and it definitely seems to be coming from the starboard side. Can you hear yours under the hatch, or just in back of the boat?