OMC 454 "pinging"

[davepepin]

I own a 1993 Chris Craft with a 454 King Cobra. I recently replaced the engine with a 454 Magnum out of a Mercruiser. The engine came as a tall block complete with the intake, carburator and a Mallory distributor and coil.<br /><br />The engine runs great until 2000 RPM where it starts to "ping" and sounds almost like a diesel engine... I can't even get up on plane. Base timimg is set at 10 degrees and the fuel tank is full of fresh 91 octane fuel (Super Unleaded). What exactly causes an engine to ping?<br /><br />Thanks,

 

[imported_scott_m]

Re: OMC 454 "pinging"

10 degrees seems like a little too much initial, seems like I have my big blocks at either 6 or 8. Also seems like your advance is coming in way too soon. Things that will make it ping:<br /><br />Too much timing<br />Lean mixture<br />Heavy carbon buildup in the cylnders.

 

[davepepin]

Re: OMC 454 "pinging"

Thanks for your help, I'll try to retard the timing a little and see what happens.

 

[LubeDude]

Re: OMC 454 "pinging"

You may be over propped also, trying to spin too large of a wheel will lug the engine.