A couple of things I've learned along the way are that mild steel will last a pretty good while, but when you wrap it with fiberglass, its life will be shortened, and if it cracks you won't be able to see it until it has the potential to do great harm. Jim Hill had glass insulation on his VW headers, and it just about made him a glider pilot one day. His oil pressure gauge dropped to zero so he made a precautionary landing, only to discover that the wire from sender to gauge had been shorted to ground because of an exhaust plume emanating from a crack in his 'glass wrapped headers. That wire was bundled with several others, and next in line was the wire that supplied power to his electronic ignition, and the insulation on it was mostly melted. I'm pretty sure that Jim said Steve Bennett at GPASC recommends against using it, and I'd concur.
Ceramic coating is a good thing, and it's cheap if you do it yourself (although not as effective as dunking it professionally). There are some details on how I ceramic coated mine with Turbo-X at the bottom of http://home.hiwaay.net/~langford/corvair/exhaust/ . The neat thing about the DIY deal is that it's dirt cheap and you can touch it up yourself in a few minutes after a repair job or adding an O2 sensor boss or that kind of thing. For the most recent exhaust incarnation, I used 321 stainless, which is a lot more expensive than 304, but will actually last when exposed to 1400 degree F exhaust temperatures. It's not so much the 304 as it is the welds that join the parts of a 304 together. Precipitation hardening sets in at something like 800 degrees, and it's just a matter of time that the now-brittle material cracks at the transition area of a weld. Even mild steel will last longer than 304, as Joe Horton's installation proves. Ceramic coating it will be icing on the cake. The 321 exhaust details are at the bottom of http://home.hiwaay.net/~langford/corvair/phoenix2/ ... Mark Langford "Yes we can!" N56ML "at" hiwaay.net website at http://www.N56ML.com --------------------------------------------------------
