There is no D to the hole, it is just turned, maybe reamed. There is an o-ring. They work pretty good, but make the intake more sensitive to being bored out in my experience. I had a bored out venutri on the plastic body and the engine ran fine on pressure bladder, but on the aluminum body it was a pain with the same bladder system. I switched to a new stock venturi and the engine ran fine again, better than ever in fact. I don't know if it is making the same power as before but it is pulling a baby flite streak just fine.
I have no idea what the venturi bore was, but it seems to be larger than recommended. A 1/8 inch drill bit floats in the bore.
I was initially concerned about the body rotating and changing the engine timing, but this won't happen as the timing is set in the case. As long as the body is lined up close enough that it is not getting obstructed there is no possible change.
Phil
Topic: Metal carb body for TD engines (Read 2275 times)