Well I mocked up 5" engine box but that still wasn't enough to balance. ..
I'm going to add 7" diameter x 3/16 thick steel plate up front to add weight.
When building plane I knew I was putting 5.7 lbs. Radial on so I beefed up tail area.
Now switching to 3.3 lbs.engine so have to add around 2.4 lbs of weight to nose as
Servos are as forward as possible. ....