Hi guys. I bought my first Norvel engine and it arrived today. I also ordered a turbo plug head to go with it as I was informed this was the best combination for the Big Mig 074 RC. I had both heads off and on the table and am now confused as which one is which. I posted a pic. Can someone help to figure out what one is what? I'm not talking about the threaded plug insert or stock button plug. I'm talking about the cylinder head (part with the fins). I've been going through Google looking at images but am coming up short. All help is really appreciated.

Just measure the inside opening. The standard head is 9mm, the turbo head is 10mm