With the engine in place the Aux or stand-by alternator ‘just’ hit the firewall. This would mean that if the alternator had to come off, I’d have to partly or fully remove the engine. This would not be good practice and it would be making a future maintenance trap.

First a hole to start.

Now you can see the problem. The alternator needed a little more clearance but I also wanted to be able to remove it from the cold side of the firewall without removing the engine. I also had to made a space for the alternator plug.

It really needed quite a big hole to get the unit out. A bit more air around the end is good for cooling too.

I made the hatch out of the same material as the firewall and I will line the rear side with firewall insulation. Probably a thin line of sealant around the edges as well to ensure no engine smells escape.

I made nutplates and these cutouts for epoxy and micro to hold them in place. I want the hatch tight against the firewall.

All done and painted. The little square just gives a bit more room for the wiring. I also put a nutplate in to hold a screw for the vent bottle P-Clamp while I was at it.