I'm building a stand off scale biplane, and it has about two degrees positive incidence in the wings and tail, from the thrustline, which as near as i can tell, is zero downthrust or sidethrust , and I have a question about changing the thrustline, due to my engine not quite fitting in the cowl. I'd like to lower the thrustline of the engine about 1/4- 3/8 inch, and I think I could probably compenstate for it by adding a bit of downthrust. The question is, how much, and how to calculate it?

How much to change the thrust line?
zero.
It can't make any difference with that minor a change.

On our Buckers, some builders commented that the models would pitch down on sustained up line verticals - they tried up trim - which they said helped - But I didn't believe it
the only fix I found was simply - More power -