Dirty Bird Posted Tuesday at 02:22 AM Report Posted Tuesday at 02:22 AM Hi 1966 M20C Mk 21 owners! I have been breathing new life into a bird that has been sitting for a while. I have an issue which might be really easy to resolve if there is an owner out there with the same model. I am looking for the routing of 1 ¼” Scat tube from the left side of the carb heat / air intake box on the 1966 M20C Mark 21. I have an illustrated parts manual that covers the 1966; however, the illustrations for that view are for 1967 and later where the exhaust system is different. I am thinking that either an owner who has pictures could show me the routing oor possibly the service manual specific to a 1966 M20C Mk21 might have a technical drawing of the routing. I can’t seem to find anything out on the web that I can download even at a fee. If someone could provide a lead I woould be most appreciative. Thanks - Chris
47U Posted Tuesday at 05:54 AM Report Posted Tuesday at 05:54 AM 3 hours ago, Dirty Bird said: I am looking for the routing of 1 ¼” Scat tube from the left side of the carb heat / air intake box on the 1966 M20C Mark 21. The carb heat dump valve duct is routed to the left exhaust cavity. I think the blue print LASAR includes with the carb heat rebuild kit shows that in better detail than the IPC or mx manuals. The actual routing isn’t critical, though, as long as the hot air is dumped overboard.
christaylor302 Posted Tuesday at 06:21 PM Report Posted Tuesday at 06:21 PM Spooky…. I’m working on the same plane (model and year), same situation, been sitting for awhile, and have the same name Mine does not have any ducting. It’s open to the air under the cowling and would be sucked out the cowl flaps.
47U Posted Tuesday at 08:06 PM Report Posted Tuesday at 08:06 PM 17 hours ago, Dirty Bird said: I am thinking that either an owner who has pictures could show me the routing 1 hour ago, christaylor302 said: Mine does not have any ducting Here’s a link to a Don Maxwell article on the vintage carb heat system. The pictures are missing, but the words describe pretty accurately. https://www.donmaxwell.com/carb-heat-systems
47U Posted Tuesday at 08:23 PM Report Posted Tuesday at 08:23 PM (edited) Pics from 2010, when I did the carb heat overhaul kit that LASAR recommended. The carb heat flapper shaft was so worn that it was eating into the air box. I had to make a little patch for it. Edited Tuesday at 08:39 PM by 47U Added pics…
christaylor302 Posted Tuesday at 08:54 PM Report Posted Tuesday at 08:54 PM Don’s article said it was vented overboard. So maybe it’s just routed the same as the other vent hoses in that area. I have oil breather, battery and fuel pump hoses all vented in the same area.
47U Posted Tuesday at 11:27 PM Report Posted Tuesday at 11:27 PM 2 hours ago, christaylor302 said: Don’s article said it was vented overboard. So maybe it’s just routed the same as the other vent hoses in that area. I have oil breather, battery and fuel pump hoses all vented in the same area. That is correct. Just stick the duct out the left exhaust cavity with all the other hoses.
Dirty Bird Posted 39 minutes ago Author Report Posted 39 minutes ago Guys - thanks so much for all the information - this is gold! Super easy just dumping out the left side. Many thanks! 1
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