Mr Maine the internal flappers is a good place to start and I'm hoping its the flappers .

Abones ..NOT A DUMD QUESTION AT ALL. ...I dont thing the knocking is present after a run on the lake. I'll have to bring the boat home to do all these test.

mike tkach I would do a compression test on the engine. That was the first start after sleeping for 7 months the cyinders and spark plugs were soaking in fogging oil so I'm not sure if that's what your hearing .I'm not a mechanic so I don't know.
The headers and rocker covers are coming off I need to see if any thing ran slack in there.

dereknkathy.. .that is my biggest fear. I know what a conecting rod sounds like and it does sound like it. I'm not pulling that card just yet.

BUP the noise is coning from behind the engine. I'll have to bring the boat home when it warms up and have a good listen.

The exhaust flappers (metallic internal) make that type of sound as mentioned. That's an easy check.

The large plenum EFI manifolds can also act as sound amplifiers and really make internal valve train mechanical noise audible. I believe this is what you are hearing. The question is this noise new or have you always heard it? Is the cam stock? When I modified my small block EFI motor (similar manifold and plenum) with a bigger cam (lots of lift) the high ramp rates of the roller cam and valve closing events could really be heard through the top of the manifold hat. It is very similar to your sound.

What about the u-joint? Does the sound change when put into gear on the trailer?

Says hear noise from rear of the engine ? Possible back cylinder(s) area or back side bottom end area. To rule outdrive totally pull it and run engine to see if noise is still there. A lot of times you have to separate the systems to figure out exactly where the noise / and or problem area is.

Could be coupler issue if drive removed and noise gone. Any change in noise if you put it in gear? How far to a boat ramp? Could stick prop in water and put it in gear.

Pull the oil filter and have someone cut it open. If it's a rod knocking, you should see bearing material trapped in the filter.

That's a darned nice Baja Force. Wish mine was fixed up that nice! I have been wanting to repaint the helm area on mine and update it like you did on yours.

I had a boat with the same motor and had a similar sound: https://www.youtube.com/watch?v=K7Z8I0CvEVs

This sound stumped everyone--oil pressure good, I even pulled the engine thinking it was a coupler, replaced all exhaust gaskets, checked flappers--Turned out to be a bad wrist pin on cylinder #8

The reason I asked if the noise goes away after running is the noise is very similar to that of piston slap and as the piston warms up (swells) the noise subsides, also it could be a tight piston pin causing the piston to rock (slap) as the crank swings, and again as the motor warms up the tolerances will change and the pin (can) free up enough to make the rocking noise subside. Now that is ONLY if the noise goes away or substantially reduces after a full warm up. Just another thing to look into, let us know what you find

Umm... same as the OP. My 502 has the same slight clicking noice after top end rebuild. No noice was there before, removed the heads and what not. R & R, and i have the same noice. Yes all pushrodsn and rockers went back in the same spot they came out. Ill be removing the manifolds and valve covers next and check to see if I magical misssed something.

Hi guys,
It warmed up a bit this weekend here in Canada and so I bought the boat home to try to rectify the KNOCKING NOISE. I did another video of the first start for the season and I think I located the knocking.
It's at its loudest on the port side - rocker valve cover. I removed the Valve cover and found some of the push rods very free to spin as well as some rockers that were loose to the point that I could shake them to get a clatter noise from them.
What's the correct way to adjust these rockers? I got to this point and need some help.

Thanks

http://i132.photobucket.com/albums/q..._194028907.jpg

http://i132.photobucket.com/albums/q..._193941594.jpg

http://i132.photobucket.com/albums/q..._185618932.jpg

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https://youtu.be/tIU_oyh3wnI

you adjust those rockers by buying ARP conversion rocker studs. there is NO adjustment with that setup. http://www.ebay.com/itm/191548584889...%3AMEBIDX%3AIT then obviously you will need either jam nuts or a set of polylocks. or upgrade to roller rockers and polylocks. but then you sometimes have valve cover clearance issues. EDIT: i just pulled out a set of net-lash bolts-balls. you can't use the rocker balls-the inside diameter is too bug for standard rocker stud. and new balls inside used rockers is not a good idea. i have no idea if they even have same outside diameter of the ball surface. so to adjust the valvetrain you need studs-rockers complete. or buy a new set of lifters. and replacing lifters on a used cam is possibly a bad thing...