I am assembling an old Fokker D-7 and it calls for the engine to be installed inverted. However I would like to put a 4 stroke in it and have heard that a 4 stroke does not run as well that way. I have also heard that adjusting properly and using 30% fuel helps. Plus onboard glo might be another solution. Any ideas?
Laurence

I have mounted many 4-strokes inverted and it rarely causes any problems. I run my regular 15% Cool Power.

About the only problem that can occur is the carb location. If the carb is too low, a full tank could cause the fuel to siphon and drip out of the carb. The trick here is to not fuel it up until you're ready to start the engine.

Yeah, that or pinch off the carb feel line. I do that anyway on my two inverted engine pattern planes. Just don't forget to remove the fuel line pinch before starting the engine. [X(]

CGr.

You can use a hemostat to reach in to the fuel line to pinch it closed. Having that thing locked on your line when you choose to start it is no problem. It'll be hanging out the front of the cowl and the prop can't get past the sucker.

I had two models that siphoned, one inverted, one at 9 o'clock. Finally got fed up one rainy day and lowered the tank in one and got rid of the uniflow routing in the other.

Take the advice about fueling and pinching. No lie.

4 stroke carbs are on those downspouts. When they're mounted inverted those are bad to trap all the carb overflow, ALL OF IT. There is no way they can avoid flooding if the tank siphons. Since they contain every bit of dripped fuel, their floods are true floods.

Ihave always had great luck with inverted 4-strokes. the only exception was an OS FL-70 which was their lower-end 4-stroke and had an air-bleed idel circuit on the carb. If I had lowered the tank, it likely would have worked OK though. Everything else has worked great.

Why would a Fok D-VII call for an inverted engine? The original airplane has the prop shaft at the bottom of the radiator, an inverted engine would have the cylinder sticking out of the bottom of the cowling in a Most unscale like manner.

This is correct, the D-VII prop/crank is low or at the bottom of the cowl. When I built mine I had to mount the engine upright to get the prop in the proper location.
Inverted four strokes are easy as long as the tank is mounted slightly low so they don't flood or vapor lock. When it's time to tune the low end is just adjusted a little on the lean side. Pumped engines have to trouble at all. I also just run 15% fuel in all my glow engines, YS and OS.

The text portion of the plans states to install the engine inverted, however, upon looking at the schematic it shows the engine upright.
I will go with that. I should have looked at that before posting. I do, though, appreciate the replies.
Thanks much.

Laurence

Problem solved

"Ready, Fire, Aim..............

Well that works better than my "Zip-Tie the tank to the bottom of the fuselage" idea!!