----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]----
I am NOT an expert on this subject but I asked a lot of questions when I wanted to do the same thing and this is the gist of the answer(s) I got: The C-85 has no provision on the accessory case for a vacuum pump. If there were such a provision, you wouldn't need an STC, you'd just install one and it'd be part of the certification of the engine. Then you'd do a form 337 for your conversion to vacuum pump source for your instruments. I've heard mention of some variant of the C-85 which had the place for the vacuum pump but if you ain't got such a variant (and I'm not sure it exists), it doesn't matter because you couldn't economically convert your engine. If you want a vacuum pump, you'll need to either: a. sell your engine and install an O-200 (not cheap but it greatly increases your climb and may be a good option when you're due for an overhaul anyway). Engine driven dry vacuum pumps are also famous for failing (300-500 hours is a number I vaguely remember) and you're really not safe depending on them without a backup vacuum system or good electrically driven gyro(s), from what I've read. b. get some electrically operated vacuum pump but then if your electrical system fails, you are SOL. c. sell your plane and get one that already has a vacuum system and IFR instruments. In practice, there are Coupes flying IFR (in NON-icing conditions) using venturi vacuum with at least one electrical gyro instrument. As a "thought experiment," I'd say you could achieve good safety, with venturi vacuum and a vacuum gauge IF you also had a backup electrical attitude indicator. But having two attitude indicators isn't cheap especially since electrical ones are quite expensive. (It's cheaper, by a big margin, than replacing your engine.) I'd also prefer to have gyros that had an automatic flag that drops to indicate when the gyro has failed. You can see why I never upgraded my Coupe to IFR capable and never got my instrument ticket. I would have done it if only I'd ever been rich. Ed Burkhead http://edburkhead.com/ [EMAIL PROTECTED] -----Original Message----- From: Bob Taylor [mailto:[EMAIL PROTECTED] Sent: Wednesday, October 02, 2002 7:00 PM To: Ercoupe Technical discussion (moderated) Subject: [COUPERS-TECH] vacuum pump on C85 ----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- In reply to James Lilly's question about an STC for a vacuum pump on a C85. I couldn't find one in the FAA's list. The parts manual lists a bevel gear for a vacuum pump or fuel injection pump for the C85 so it's quite possible. The overhaul manual, however, does not list a vacuum pump as one of the options on a C85. Contact me off list for the gory details of how I know this. Bob Taylor ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm ================================================================== TO UNSUBSCRIBE go to: http://ercoupers.com/lists.htm
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