5.7 Merc Rattling Chattering Noise

[DanielR]

New Engine, 5.7 Chevy roller, 1Hr on it so far.
I'm experiencing rattle noise starting from 2500RPMs and above.
Running Rochester Quadrajet, No water in the water separator (OE Mercruiser), New plugs .035 gap, New wires, New Coil, Timing set 8BTDC, Running Mercruiser OE oil and filter.

Engine idles great and runs great as well, up until 2500rpms when noise starts.

Do i have to adjust the valve lashes, or this is more common due to running lean. Reason im asking is, this is brand new engine and I've never heard what sound lashes make so I cannot compare.

Thanks
Daniel

 

[Bifflefan]

Re: 5.7 Merc Rattling Chattering Noise

Valves make a clicking sound.
Rattles are usually something left loose.

 

[DanielR]

Re: 5.7 Merc Rattling Chattering Noise

Sound is similar to chain rattle, or cover that was coming loose (which is not).

 

[EddiePetty]

Re: 5.7 Merc Rattling Chattering Noise

...post back and give us an idea as to the color and condition of the spark plugs. Additionally, is the sound more noticable ramping-up, steady throttle or coming off the throttle? Does the sound vary under any of the preceeding? Is the sound more/less noticeable straight ahead, gentle heading variance or sharp turns? What is the oil pressure when the sound is noticed? Does the temperature elevate with the length of the sound?
Check your TOTAL advance and report back.

 

[DanielR]

Re: 5.7 Merc Rattling Chattering Noise

Currently used is Thunderbolt IV System.
Noise becomes noticeable starting from 2500rpm, and the higher the RPMs the more pronounced is the sound. I haven't reved it past 3200, but relatively the higher RPM the louder rattling becomes.



*EDIT*
I have just realized my timing is off my factor of 2. I dialed my timing light to 8, but i have set it on the engine mark to be 8 as well.

I will get back to you once i set CORRECT timing.

*EDIT2*
Engine is running fine. Wrong timing caused the rattle, dummy me...