Coupes, Continental and High Lead

[Stefan Fanselow]

Dear Coupers,   I am about to purchase a Coupe (well, an M-10) for shipment to Japan and to fly it around here for the fun of it. For those interested in the logistical issues, this will be done by crating the plane, putting it into a container and bring it over by ship. Too long a distance to fly. This is going to be the only plane of its kind in this country, so we'll have fun around here.   Now the serious matter: In Japan, there is no such thing as 80 or 100 LL Avgas. The only available type is 100/130 Avgas. According to the specification sheet, the lead content of this fuel is significantly higher than 100LL or 80. I am not a chemist, but learned that the 4-Ethyl component of 80 octane Avgas is 0.5 cc, 91/96 and 100 LL is 2.0 cc, 100/130 is 3.0 cc. At least in theory, this makes 100/130 AvGas contain six times as much lead as 80 AvGas.   What does that mean for the operation of the C-90 engine? Too high lead content makes spark plugs foul easier, is that right? But would it be unsafe to operate the engine with 100/130 Avgas? If it is safe, what can one do to prevent or slow down spark plug fouling? Use Iridium plugs? Mix the Avgas with (lead free) autogas (no alcohol, and it has 100 octane here)? If so, I guess I still would need an autogas STC? Or just accept the fact, lean the mixture as much as possible, and check and clean the plugs regularly?   I'm looking forward to the expertise of the members of this group, which was a tremendeous help so far.   Greetings from Mount Fuji   Stefan