Ok, well, the engine of choice for this particular airframe I am dealing with is a Valach 170, gas. All mine are now gas. Most planes be it kit, ARF or what ever end up with a pretty closed up firewall between the engine and airframe. But this one is not so because of the orientation of the carb, rear and offset low. The pics 1 & 2 are a front and rear view and that opening went all the way through, but I have closed it off as seen in pic 3.
So by the responses I did the right thing. Great!!