340 Pinging using 94

If you have time can you do the cranking compression test please. While the spark plugs are out record the number on the spark plug and report back. Couple of pictures of the spark plugs would be nice. if you can get some timing numbers through the rpm range that would be awesome. I'll bring this up. Do you know how to check the tdc mark on your balancer? If you do, check it before you do the timing check otherwise don't worry about it just yet.

Likely The reason the ping doesn't happen until the engine warms up is because the combustion temprature is lower. Higher combustion temps will bring you closer to the conditions necessary for ping to occur. A manifold heat cross over valve stuck closed will increase combustion temps. Do you know if you have one of these in your exhaust system. Or maybe you have headers? A picture of the engine would be nice.

The fact that the pinging doesn’t start until the motor is warmed up and reducing the timing reduced the severity of the ping does lean towards the sound that your hearing as actually being ping. However it could still be something else. More information would help narrow it down. Good luck.

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