I have the Vectorflight 66" Extra 300S and need a spinner for it. The engine is a Supertigre G-90 and the diameter of the backplate that came with the engine is 1.5" The problem is that I bought an APC 13 by 8 prop and it's way to big for the holes in the spinner. The holes aren't even shapped right for the prop I've got. They are way too slender and slope forward towards the point of the spinner. The guy at my LHS told me I'd have to go to a machine shop and have it specially drilled out. That doesn't sound right to me so I thought I'd see what everyone else is using.

I dont have that model but have a few ST.90s with spinners. All the plastic ones have to be trimmed. I don't know what the spinner companies are thinking. Making a 3-1/2" spinner that's only big enough for a 9x6 prop. It sound like yours is metal. I have several Tru-Turn spinners. They are more than big enough. What brand is yours? If it is metal(ALUM) you could open it up your self. All the ALUM ones I have seen have a hole in the center to bolt on. This hole can be used to run a prop balancer through.

David