I am installing my first gas engine after flying mostly nitro engines and i have a question. I am replacing a O.S. 91 FX with a DLE 20 but the throttle servo sits lower than the throttle arm any suggestions on what to do in this situation?

Not able to get my head wrapped around your issue, but just wondering, you understand that with the pump in the gasser's carb, you're able to put the tank about anywhere in the plane? For that reason, many put them on or maybe just ahead of the CG/wing tube, leaving the area in back of the firewall wide open to mount the throttle servo about anywhere pretty easily. Fuel tank on CG means no/minimal CG shift from full tank to empty.

Picture stolen from somebody, not supplied to promote Z bend at carb arm, but to show potential for "less than straight" pushrod from servo to carb arm. It doesn't necessarily need to be straight.

Apologies ahead of time if I've completely misunderstood your question. -Al

Follow ahicks advice regarding tank location then relocate the throttle servo to a convenient location that aligns with the throttle arm on the carb.

The metal throttle pushrod is probably a lot bigger no-no than the z-bend (just sayin').

I use metal pushrods with ball links at each end for throttle pushrods in most of my airplanes. These can vary from just a few inches long to 18" or so .... all with zero problems. With modern radios, I'm not sure what the issue might be here.

If I use a metal pushrod, I like to have a nylon link on one end to stop unwanted RF - also known to "Kill" those planes on 72 and probably 27