I have an importand message for you. If the location of the ignition makes adifference in range checking then there is something else wrong and you need to find it and fix it.

I have had dozens of installations with all different orientations. I've had the throttle and/or choke servos as little as 3 inches from the ignition box. Never had a range or interference problem as long as everything was working properly.

Problems occurred when I had one of these problems;

ignition that had been in a crash

abraded shield on the plug wire allowing arcing from the center lead to the shield

receivers that had been through a few crashes

wrong crystal type (used a Hitec crystal in a Futaba PCM receiver)

extensions with bad connectors

bad servo feeding back interference

2 receivers interfering with each other

and a few others.

Each of these allowed the radio to work but not properly.

You need to find the underlying cause, reorienting the ignition is a bandaid when you need surgery.

TF