Timing Too Advanced

[bassattacker]

Hello again, I've got a 3.0L Mercruiser Alpha 1 outdrive, in a 1998 Tri-toon.

I had the engine replaced about 8 years ago buy a local shop, I called to see if they had time to drop if off, and they told me "we don't work on i/o pontoons". I said, "You put the motor in this one", and they replied "Yeah, thats the last one we'll ever work on!".

So here I am, shade tree mechanic, trying to solve an issue with timing advance.

I hear a helluva rattle under load at high RPMs 3000-4000. When I back off the throttle the knocking goes away.

I checked my base timing, its at 2 degrees ATC, with the distributor wires jumpered and the shift interrupt switch jumpered. This is what the air cleaner says it's supposed to be.

However, when it's warmed up, and I pull the jumper from the distributor wires and reconnect the shift interrupt switch its running 20 degrees BTC. I replaced the ignition module thinking perhaps that was my problem, but I'm still at 20 degrees BTC.

Any suggestions on next steps?

 

[Grub54891]

Not sure myself, just following along.

 

[Bondo]

Hello again, I've got a 3.0L Mercruiser Alpha 1 outdrive, in a 1998 Tri-toon.
So here I am, shade tree mechanic, trying to solve an issue with timing advance.

I hear a helluva rattle under load at high RPMs 3000-4000. When I back off the throttle the knocking goes away.

I checked my base timing, its at 2 degrees ATC, with the distributor wires jumpered and the shift interrupt switch jumpered. This is what the air cleaner says it's supposed to be.

However, when it's warmed up, and I pull the jumper from the distributor wires and reconnect the shift interrupt switch its running 20 degrees BTC. I replaced the ignition module thinking perhaps that was my problem, but I'm still at 20 degrees BTC.

Any suggestions on next steps?

Ayuh,..... Welcome Aboard,...... Is the fuel filter clean,..??
Is the carb, 'n rest of the fuel system up to snuff,..??
A lean condition, is the quickest way to cause detonation,.....

 

[kenny nunez]

Take a close look at the starter where there should be a bracket that connects the field frame to the engine block. If there is no bracket then it was left off when the engine was replaced. 3.0s vibrate and if the bracket is not there the starter drive will make a lot of noise inside it’s shift fork. The noise is probably amplified in the aluminum engine bay. The only other noise could be a loose flywheel.