I would like some advice on mounting the CDI ignition unit for a gas engine.
My concerns are that it needs to be up front near the fuel tank, and the ignition lines and fuel lines passing through the firewall close together.
How do people normally secure the CDI igntion units, batteries etc.
How much seperation from fuel system is required.
I understand as much seperation from Radio gear as practical is required.

I have read the newbie thread in this forum but could not see any advice on this particular issue.

separation from the fuel system doesn't really matter as long as the braided ignition wire doesn't wear through the fuel line or something. As far as mounting, foam isolate it like you do your receiver.

Thank you

Foam and tie wraps, usually up on the firewall box if it will fit is where I put mine. Space the battery according to weight needs.

You should always keep every component of your ignition system and radio system separated by at least 12 inches or as much as possible. Never have any metallic object in that 12 inch isolation area including a metal pushrod to the engine and especially a throttle servo. This advice holds true whether you experience interference or not on the ground or if someone else tells you that it's BS because they have gotten away not doing it. It will catch up with them one of these days. Dan.

I worked on my first gasser this year as well and got some great feedback from some of the guys helping you now. The picture below is how I did mine. You didn't mention what kind of plane it is, so I don't know what kind of room you have. I have a Rascal 110 so there is plenty of room behind the firewall, though it's not real easy to get to, but not under the cowl. The tray that's in the picture has a screw through the firewall holding one end and the other end is screwed into a block that I CA'd in at the back.

In my limited experience, you should try and fit the ignition moduel as close to the engine as possible (obviously not in the direct line of the exhaust. The battery should be close too, but can be more dicted by CoG needs.

Make sure you use a non-metal pushrod from the throttle to the throttle server. Use a Sullivans plastic pushrod or similar. For my first gasser, I used a metal pushrod and got a brown out on my first landing approach (from the ignition spark being transferred along the metal pushrod back into the server and the resultant voltage spike causing the receiver to re-set. While the plane was fixable, it took me 6 months to get the replacement part I needed for my engine.

I have been running metal push rods on all my gassers for the last 8 years with no problems at all. I use dubro ball links on the ends so there is no metal to metal touching on he push rod. The problem with ny-rod etc is that it will change length with heat or cool throwing off precise idle.
If the spark is jumping or transmitting an arc there is something wrong with the shielded ignition.

I'm with RTK on this. I use a metal 4-40 rod with ball links and have never had a problem. And this is on 72 mhz. It gets frustrating trying to keep a consistant idle with ny-rod

Thanks to everyone for the advice. Best to be safe.
My first Gas Plane is a great planes Giant stick ARF.
I have been flying glow and some electric models and slope soarers for years
Also designing a 1/6 scale Hellcat for Gas engine.
Have designed and built a 1/12 scale electric PV1 Ventura that goes well.

Cheers, happy flying.