273 commando Build

Newbomb Turk said

At what rpm is the timing in. There should not be brown on the plug. That’s fat.

Edit: At your compression a 9 is too cold.

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Agree. The 9's are too cold. I converted to Autolites and somehow ended up with a 8 heat range. I always had a rough/rich idle I couldn't tune out. I switched to 12's and it immediately cleared up. They have been in for 10 years now.