detonation / knock issue on 340

Updates. Found the carb base plate is cracked. So I’m in search for a good replacement. I did do a compression test. Highest cylinder reading 180 lowest 165. The plugs I just put in 30 miles ago look like this. Guess I’ll continue the work after either I find a replacement base plate or a carb. I’ll follow up once I’m back into it

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Dead lean, some of which being caused by your busted carb plate. Timing is way shy.
This may help
FBO Ignition - Home of the HRR688 - Spark Plug Reading