I have a Top Flite Cessna 182 that I am assembling and I want to install a Zenoah G20. This will be my first venture into gas engines. The firewall has the center lines marked. How do you determine the thrust line of the engine and the mounting points on the firewall?

Birman

The prop position on the cowl determines where everything goes

The engine manual should have a dimension drawing showing the thrust line relative to the mounting holes. If not, likely someone on this forum or even the Zenoah dealer would have this information. Good luck.

EDITED !!

w8ye, no I'm not fallowing you around LOL,,

the Gassers I have worked on (from 73 inch span to 82 inch) called for the Back of their Props to be mounted 6&1/2 inches from the Engine Wall, and these Planes called for at lest 2 Degrees of Right Thrust,,

it's very easy to use a Protractor,,
with 2&1/4 Degrees of Right Thrust/Back of Prop 6&1/2 inch from the Engine Wall you will need an Engine Offset of 3/8 inches,,

and it may also be a good idea to give half that in Down Thrust..

if you have the Prop distant to Wall, and the Thrust Angle numbers you need then all you need is a Protractor to get the Offset,,

then set your Engine on the Wall and mark your holes..


Jim

The Zenoah G20 is 120mm from the back of the mounting plate to the back of the prop. That is 4.72"



http://www.horizonhobby.com/ProdInfo...0EI_manual.pdf

EDITED,,


well at that it's,, about 3/16 at 2&1/4 Degrees,,

but it's the design of the Plane and Balance Point that determine how far the Prop is mounted from the Engine Wall !!

Jim