I tried those plugs about 20 years ago when Moroso started selling them and almost burned my car to the ground. I set the float level and left the plugs in the carb and did a quick trip around the block. Had a bad stumble going around a corner so I pulled over and lifted the hood. One of the plugs had melted or dissolved and fuel had spilled out of the bowl while going around the corner. Just had a little flash fire but it didn't get back into the carb. I walked home and got the brass plugs and that was the end of that.