There were a few 7GCBC's with field approval for Lyc 0-360/180. Don't know of any with constant speed prop. I flew one a bit some years ago. Kinda nose heavy, but manageable. Pretty rare though.
The 8GCBC "Scout" was better all around, though a bit heavier. Hartzell CSP a factory option, though some nasty AD's on the prop.
supercub, there are a few STCs that allow you to install the 180 Horse and Constant Speed Prop on the 7GCBC. If you go to the FAA.gov Website you can do a search for 7gcbc STCs and get about 99 STCs. http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgSTC.nsf/MainFrame?OpenFrameSet
STC SA742NW is for installing the Lycoming O-360 and Hartzell CS Prop. STC SA283AL installs another Hartzell Hub, Blades and Governor. STC SA00464DE installs the Lycoming O-360 and McCaule Prop. STC SA00096BO Installs the Lycoming O-360 and Sensenich Prop.
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