Matt's RV-7 Project

I mounted my firewall ground block on the upper part of the firewall, pretty much directly above the battery box, with enough room below it to replace the battery without hassle. You can see that the brass bolt B&C sent with the ground block kit is absurdly long. Next time I order another batch of electro-goodies I'll have to remember to ask them to throw in a shorter bolt for my firewall.

Here's the cabin side of the ground block, where you can see there are a lot more grounding tabs. I sprung for the biggest size (48 terminals) because I'm not sure how many ground points I'll need and I didn't want to run out. You can also see that I added an extra bolt (left side) to support the thing, because it seemed like it needed more attachment strength over there.

Here's a nutplate I installed that will eventually hold a clamp for the breather tube. It's right next to the heater valve I installed last night.

I drilled a pilot hole for the throttle cable, in the location specified in the plans – low and approximately in the middle of the firewall.

The mixture and prop cables come through higher up, on the left side of the airplane. The mixture cable hole was fine, but I couldn't put the hole for the prop cable in the spot spelled out in the plans because my parking brake valve is right there. In order to make it work I had to move the hole 1 3/4" to the left side of the airplane. This is probably a blessing in disguise, since apparently the stock position requires the prop control cable to have a pretty tight bend, which will be somewhat relieved by moving the hole further outboard. The only downside is that I'll probably have to use a cable with an unknown amount of extra length on it.

Looking from the inside, you can see that the prop and mixture cables will clear the parking brake on either side, whereas the plans position would have put the prop cable right underneath where I'd previously decided to put the parking brake valve. I suppose if I were smarter I would have done a better job of reading ahead when I installed the brakes, but oh well.

I drilled the bolt holes for the transducer manifold, but I can't attach it permanently until I get the subpanel ribs riveted on. That will in turn have to wait until I get a little further down the road, avionics-wise.

Not shown are a couple other locations where I drilled holes that will eventually allow various things to be bolted to the firewall. I think I'm nearly done with the firewall stuff that needs to get done before the engine arrives, with the exception of expanding the control cable holes up to full size and riveting on the firewall recess for good.

Cabin heat in most airplanes comes from a heat shroud on the exhaust system, which warms up the air before passing it through a heater valve and then to the cabin side of the firewall. The heater valve that Van's sells is made of aluminum, which will melt at a much lower temperature than the stainless steel firewall. I decided to spring for the replacement stainless steel heater valve made by EPM instead – I bought mine through Avery for $99. That's $34 more than Van's part, which I figure is worth it to not worry about the potential of having a big hole in the firewall that doesn't keep fire out.

I used one of my fancy hole cutters to put a 2" diameter hole in the firewall where the heated air will pass through into the cabin:

The steel heater valve comes with a small tube of Biotherm 100 sealant, which is pretty neat stuff according to the datasheet. I applied a gasket of Biotherm to keep fumes out of the cabin.

Here's the valve bolted in place, viewed from the engine side of the firewall:

For posterity, here's the cabin side too. Since it's bolted straight to the firewall without any extra stiffeners, I used wide AN970 washers on the back to spread out the load. Probably overkill but that's how I roll.

Since Biotherm seems like such useful stuff, I ordered a whole tube of it from Diamond Tool. There'll be plenty of places to use it on the firewall to keep bad stuff out.