I am using Enya's own venturi part number 09422 that seems to work fine. Venturi size is 6mm and shanks size 7mm.

That's the one I have. What prop works on yours?

Motorman, I've only static run my CL version. Would like to comment more but can't. Bought 2 of them in NOS for my Sterling 36" Profile Lockheed P-38 Lightning, but haven't started the kit yet.

I've run the RC version, the .09-III TV, works well with NOS 7x6 wood Top Flite props. Haven't tried the 8x3 or 8x4. One other flier's been using 8x4 props, says they work really well.

Peter Chinn's observations in the engine test articles on http://sceptreflight.com/Model%20Engine%20Tests/Index.html that there is no use using props less than 7x4. I flew an RC plane on an APC 7x3, it flew very .049 like, but moved out really nice with a 7x6. Has to do with peak HP developed at a lower than Schneurles RPMs, makes it work well with a larger diameter / higher pitched prop.