Gapping and indexing plugs on 250-300 XS engines

[Jr in Jax]

Indexing and gapping plugs on 2018 300XS

While I was at Silver Glenn last week I talked with Trace on S&F about his 300XS Intimidator. I was complaining about my engine surging while getting on plane and he told me a plug change/fuel filter change solved the same problem on his. I read everything I could about the IR-M plugs and found a video from Mercury Racing on indexing the plugs to get the maximum flow across the electrode.
I indexed my old plugs before removing them and found 4 out of 6 were indexed wrong and all of the had the wrong gap [.030 instead of .040].
I indexed the new plugs with the .040 gap. I also cleaned the stopped up inline strainer supplying cooling water to the compressor.
Hope to test tomorrow before the storm arrives later in the week.

 

[Lotus 50]

I bought 12 spark plugs in the spring and on one hole I didn't get a decent index until the 12th plug. It wasn't great but it was acceptable according to the diagram I downloaded. The 200XS plugs are something of a pain to access. How are the big block plugs?

 

[ssv1761982]

I bought 12 spark plugs in the spring and on one hole I didn't get a decent index until the 12th plug. It wasn't great but it was acceptable according to the diagram I downloaded. The 200XS plugs are something of a pain to access. How are the big block plugs?

Can you post a copy of that indexing procedure?

 

[Lotus 50]

 

[Lotus 50]

My 12th plug was barely in zone b