engine rattles after 3000 rpm

[roseran]

I just picked up a 21ft larson with a blown 5.0.l volvo penta. I bought a used engine with 112 hours on it and installed it. before starting it I replaced the carb, starter, plugs, wires, distributor cap and rotor. I checked the timing and it is at 10 degrees btdc. when I put it in the lake it started perfect, after I got out of the no wake zone I brought her up on plane no problem and was cruising at around 2800-3000 rpms. the problem is that after 3000 rpms she starts to rattle bad (valves) not sure how old the 1/2 tank of gas was and put 10 gallons in with it. any ideas

 

[Bondo]

Re: engine rattles after 3000 rpm

I just picked up a 21ft larson with a blown 5.0.l volvo penta. I bought a used engine with 112 hours on it and installed it. before starting it I replaced the carb, starter, plugs, wires, distributor cap and rotor. I checked the timing and it is at 10 degrees btdc. when I put it in the lake it started perfect, after I got out of the no wake zone I brought her up on plane no problem and was cruising at around 2800-3000 rpms. the problem is that after 3000 rpms she starts to rattle bad (valves) not sure how old the 1/2 tank of gas was and put 10 gallons in with it. any ideas

Ayuh,.... Welcome Aboard,.... Yer probably seein' what Killed the ole motor,.. Detonation,...

I'd also guess is from a Lean condition due to Bad gas, water in the gas, or a fuel system failure, possibly the carb itself,...