Mike,


I would try first the APC 13x4w, seems this prop can be re pitched with heat to get exactly what you need.

If the engine doesn't kick in higher rpms when the nose goes up just open more the venturi. We are using the 8.00mm venturi and no muffler pressure.

One option would be the Zinger 13x4 3 blades. The Bolly 13x4.5 actually comes with less then 4" pitch and we had to add a little more pitch to fly in the speed we want so this Zinger w/ 4" pitch sounds about right.  The problem with the Zinger 3 Blades is the weight, it has two thick aluminum disks that hold the blades together  and the blades are too thick. You'd need to thin out the blades and work some of that aluminum off. But it is a cheap solution for a 3 blade prop. And also they don't fit well on spinners the aluminum disks are 2" in diameter perhaps more. I have one of these props, and what I did was cut the disk straight from the LE of one prop to the TE of the next, the disc now looks like a triangle. I will  try to fit the prop in the 2" Aluminum Spinner from Brodak, it won't be easy and it will not look sharp either, as the holes will be big and it will show part of the aluminum that hold the blades together.

Keep me posted how you are doing with your Engine.

Martin
p.s I am using 8mm venturi with a bigger prop then APC 13x4W, so  I guesstimate that with the APC 13x4w you will not need to change the venturi, if so, it will be just a little bit.