M

mlwynn

Well Known Member
Hi all,

I am building the fuel system prior to riveting on the front skin. Looking at it, I can't imagine what a hassle that must be to do with the skins on.

I am using an IO360 with a AFP fuel injection (on order, not yet here). I need to plumb for a purge return line. It would be most convenient to place the firewall pentration about an inch or two outboard of the fuel line pentration. As I have exactly zero idea what stuff ends on on the firewall later, I have no idea if this placement will interfer with other stuff and or will be really difficult to plumb from there to the purge valve.

Does anyone have a picture of their firewall and/or an answer to the best place to put this fitting?

Regards,

Michael Wynn
RV 8 (Pre-punch) Fuselage
San Ramon, CA
 
http://www.rvproject.com/20030516.html

That page has photos showing where I installed my purge return fitting in the firewall. Right next to the fuel supply line, through the same doubler.

Next time I would not put it there. It requires a relatively long hose to run all the way down there.

I would put the bulkhead fitting toward the upper right side of the firewall, keeping the hose run from the engine to firewall relatively short (CHEAPER & LIGHTER HOSE!). I'd have more aluminum on the back side of the firewall, but that stuff is cheap & light.
 
Forgot to mention...however you run the purge return, make sure it doesn't interfere with your oil filler tube.
 
Thats where I put mine

works great and my return hose just misses the oil filler tube as Dan described.

Frank
 
Line placement and reinforcement

Thanks for you insights, gents. Sounds like the best thing may be to wait until I have the engine and accessories hung before I penetrate the firewall.

Dan, I noticed your use of aluminum backing plates. I had not thought of that before. No question, the ss firewall is pretty flimsy material. Do you suggest backing plates for everything attached to it? If so, how thick? Does it matter if the backing plates are forward or aft (other than dealing with the bracing behind the firewall)? It looks like most of the mounting stuff has to be done with the engine hung and the accessories and their locations sorted out.

I have yet to figure out exactly what has to be mounted to the firewall. Oil cooler, starter solenoid, master contactor, voltage regulator, battery(? here or in the luggage compartment area?) Anything else I am missing?

Regards,

Michael Wynn
RV 8 Fuselage
San Ramon, CA
 
I just copied what Van's did in other areas in terms of .063" aluminum doublers for various firewall penetrations. Brakes (taildragger), gascolator (carb'd), etc.

I don't have the dwgs in front of me but I'm pretty sure he called out a doubler for the fuel supply penetration, so I just enlarged it to provide for the purge return bulkhead fitting on that same doubler.
 
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