ORIGINAL: speedracerntrixie
In 35 years of R/C flying I have never set up a tank so that the clunk moved to the front of the tank.
While not always or usually done, there are plenty of workable ways of doing this.
I don't bother though as there is something to be said for simplicity.
As you say the engine should handle downlines if it is not overly leaned.
ORIGINAL: speedracerntrixie
Holding the nose down while the engine is running is a useless test.
Nonsense, his engine is not a usual gas engine setup. It requires tank pressure to function correctly.
A nose down test while on the ground will both help establish if the engine is too lean and also help reveal other potential plumbing issues.