Can you cut a firewall

[topflight36]

HiI was wondering if it is safe to cut the fire wall on a plane to stick the Carb of a engine through. The reason I ask is I have a 34% planes plus extra that I picked up. I would like to put a DA-85 in it but the only way that it will fit is if I flush mount it to the firewall. But as you guys know the carb sits in the back. Please any help will be much appreciated.

Thanks Tom

[Hinckley Bill]

Tom,

Haven't personally done it but I see it done in threads on FG all the time, as many engines have the rear carb mount.

I'll leave it to the "experts" to provide additional information and guidance but I do believe a couple of areas of concern that always needs to be addressed are gasoline "spitting" back into the airframe as well as sufficient air flow getting to the carb.

Bill

[Dan767]

I've done it twice, no problem. 3W-75i and 3W-80xiCS on two different airplanes. I use card stock and make a template.

[~SnApRoLl]

I have seen where people have cut holes in the firewalls for carb clearance with no issues. In fact I had to do so on my 2.3m Compy so the carb on my 85 would pass through. Here are a few pics. Now the stand offs you see are only temporary and I made a 1 inch spacer / engine mount out of 4 pieces of 1/4" ply that I laminated and I cut out a backing plate out of 1/8" ply that I wil glue behind the firewall for added strength.

Hope this helps.
Shawn

[MikeC3D]

http://www.flyinggiants.com/forums/f...-new-post.html

This build thread may give you a few pointers on how it should be done.

[topflight36]

Thanks guys

[thewrap]

Yes you can. Some plane and engine combos you really don't have a choice.

[Pistolera]

Here's how I eliminated slobber in my motorbox; http://www.flyinggiants.com/forums/f...take-tube.html

Works great.
Earle