I think it is an OS Max 3.5 but not sure.

The carb and exhaust cooler is aftermarket.

If anyone has this block I would like to know the neck size of the carb and exhaust hole spacing and opening size, or know where else to look.

I am hoping the carb and the header will fit an OPS 3.5 SE which I have dimensions for.

jp, are you 100% certain it's not a Master?

Did any of the r/c boat companies, like Dumas, for example, ever have engines made for them? Similar to the way Gilbert had Fox design engines for them?

David

Master is/was a model by Chipolla of Italy. I believe the Master is a .24.

Well, looks like I am stuck then with never knowing if the parts will fit my little OPS if it is an uncommon motor. I would hate to buy it just to find out the aftermarket parts cant be used with my engine, and getting parts for this one sounds impossible.

CB Marine who makes the aluminum parts is out of buisness now, so even cross referencing that way is out of the question.

Dave mentioned a good point, and not really sure about that other than maybe Octura with K/B? Don't really know...