Thanks! I'm about to head down to the airport to put up some more selkirk rubber foam. Can't wait to fly it all insulated. I flew it without any insulation over the weekend and it's pretty noisy.
Frank - I'll have to go look at the primer, but it's a self etching primer that our IA really likes. We got it to spray on with the gun, but then got a rattle can or two to get the hard to reach places. So far it seems to work pretty well. MEK for the black goop of death and lots of blue shop paper towels. Once the MEK evaporates off that stuff, the black goop sticks to anything it touches. I applied the MEK to the goop with a brush, let it set for a minute, then scraped the wide areas off with a plastic scraper. That seemed to get the majority of it, but the parts in the corners, around the rivets, etc. were a pain in the butt. Lots of patience and time with MEK, a nylon brush and paper towels. We also burned through a lot of those red shop towels on the tougher spots around rivets that just ripped the paper towels to shreds. I kept expecting my trash can to spontaneously combust, but so far so good.
Oregan180 - The firewall is the Selkirk foam again, but in 1/2" thick. I'm hoping it stays up pretty good, I do not want to have to do that again any time soon! It really doesn't get that hot back there on our 170, so it's mostly just for the noise. I also used some 1/2" aluminum spacers from the Aviation department of Home Depot to put the cable that opens and shuts the heater (great on the pilots toes, horrible everywhere else) vent on top of the foam instead of behind. It was previously mounted flush to the firewall. Also, we pulled as many of the screws that came through the firewall and switched them so that the heads were in the cockpit and the pointy ends are on the engine side. That way it was easier to just put the foam over the top of them.