Distance from ingition box and electronics? ??
 

Engine book says 12"" from ignition to servo / electronics ....
having trouble balance with all servos that far back?
Any ideas?

What engine? That's old news, 2.4 isn't as susceptible to ignition interference. Throttle servos near the ignition box is usually no big deal and a few inches is ok if you can get it, don't take that as a hard and fast rule.

That said, always have someone restrain the plane and do a range check with the motor running.

The interference path is not through the receiver, the long wires between receiver and servos are the right length to be antennas, the wiring picks up ignition leakage from the ignition system, which happens to be between 0-20KHz, the same frequency (range) as the servo signal wire lead.to the servo amplifier (the servo signal is narrower, but includes the ignition range). Any ignition wiring or components HAVE to be at least six inches (more is better) apart from flight control system wiring or components. The particular radio frequency is not a factor. Ignition interference servo hard overs can affect 27, 50, 72, 75 mhz, AND 2.4 GHZ radios alike. They all use the original servo signal system developed many decades ago. Receiver battery packs too close to ignition components (like switches) can cause interference also.

Twisted servo wiring is effective in damping or attenuating outside interference, you can buy servos with twisted leads. When we changed to 2.4 GHZ I thought the interference issues were over, I was flying electrics and sailplanes at the time, when I put 2.4 GHZ radios into my gas powered warbirds, the interference problem came back. When I took a look at the issue I thought I had solved, I found I had forgotten my lessons, throttle servo wiring in the same bundle with ignition leads.

Engine is new DLEl 40cc twin.
radio is spectrum .
Plane is biplane , built around heavy radial that was more trouble than I want to deal with
CG is front of bottom wing so not much room up front..
I'm thinking after I move all servos back from ignition plane will be tail heavy
Its my first gasser and I guess it would have been easier to go with glow.
Question...I read somewhere that length or distance from firewall to prop is not critical so if I make standoffs longer and move
Engine forward this will help me balance without adding nose weight..? Right?

Thanks for feedback guys

I have done that with several planes, the only difference is a slightly slower snap rate. Didn't affect the plane's looks much, nobody noticed. I moved a Saito 180 3 inches forward on a Cap 232 when I pulled the gas engine out, the weight and balance issue was the same as yours. Do it. You can build spacers to fill any gaps, and a lot of the old Classics had air behind the engine. Where I lucked out was the Cap had a long engine cowl, I could put the engine anywhere I wanted.

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. ....

Ni