Which engine for Waco bipe?
 

Picked up a 1/5 scale 72" Waco biplane and need advice on engine selection. Two engines available but both will require modification to airframe. 1-Quadra-35 / 18x6-10 prop. 2- RCV 120 / 18x12 prop. Which of these engines will give the best performance on this plane, when painted and finished out, should weigh in at about 12-13 lbs?

Which engine for Waco bipe?
 

The Quadra would be too heavy for a bipe this size and weight IMO.You would have CG problems too, I think.
The RCV option would be my choice of the two you gave us....

Which engine for Waco bipe?
 

If you want to run gas, look at the RCS 140. It will have no problem with the 18-inch prop and will give you that "gas" sound. From what I have seen they produce about 15 pounds of thrust giving you better than 1-1 thrust to weight. They are only slightly heavier than the same size 4 stroke. The RCV would be my choice of the two you listed. :)

Which engine for Waco bipe?
 

Is this the Pica kit? Or Icon West?