Pietenpol-List: impulse mags
Posted: Thu Feb 09, 2012 10:37 pm
Original Posted By: "Clif Dawson"
I flew 41CC behind the A65 with two different mags (left and rightmags were different). Neither had impulse couplers and the olderone was a Scintilla "lunchbox", probably as old as the engine.Still threw a great spark.The A75 on the airplane now has matched, brand-new Slicks andthey both have impulse couplers.Honestly, I don't notice any difference in ease (or difficulty) ofstarting, probably because the compression is so low, the prop isso long, and I try to keep everything in a good state of tune. Ican't comment on starting a Ford without impulse coupling, but myexperience with my Continentals has been fine with or without.That plus the key to hand-propping these engines is finding theright starting routine and following it exactly, every time, andincluding whatever types of sprinkling pixie dust in the air orswinging a dead chicken make it work for you. There is also animportance to what you do when you shut the engine down, too. Ifyou shut off the fuel valve as you taxi up to your hangar and thenlet the engine sputter and die as it runs out of fuel before youkill the mags, it will start differently than if you leave fuel onand shut it off with the mag switch, leaving fuel in thecarb bowl. It will also start differently if after you turn offthe mag switch and as the engine is spinning down you roll thethrottle forward (open) instead of leaving it at the idle stop.I do not have a fuel primer; I pull it through a couple of bladeswith the throttle back at the stop so it will pull fuel throughthe idle circuit (Stromberg carb). It will usually start on thefirst or second blade after I go through the proper motions.Sprinkling the pixie dust works for me ;o)Oscar ZunigaAir Camper NX41CC "Scout"Flying Squirrel N2069Z "Rocket"Medford, OR website at http://www.flysquirrel.net ________________________________________________________________________________
I flew 41CC behind the A65 with two different mags (left and rightmags were different). Neither had impulse couplers and the olderone was a Scintilla "lunchbox", probably as old as the engine.Still threw a great spark.The A75 on the airplane now has matched, brand-new Slicks andthey both have impulse couplers.Honestly, I don't notice any difference in ease (or difficulty) ofstarting, probably because the compression is so low, the prop isso long, and I try to keep everything in a good state of tune. Ican't comment on starting a Ford without impulse coupling, but myexperience with my Continentals has been fine with or without.That plus the key to hand-propping these engines is finding theright starting routine and following it exactly, every time, andincluding whatever types of sprinkling pixie dust in the air orswinging a dead chicken make it work for you. There is also animportance to what you do when you shut the engine down, too. Ifyou shut off the fuel valve as you taxi up to your hangar and thenlet the engine sputter and die as it runs out of fuel before youkill the mags, it will start differently than if you leave fuel onand shut it off with the mag switch, leaving fuel in thecarb bowl. It will also start differently if after you turn offthe mag switch and as the engine is spinning down you roll thethrottle forward (open) instead of leaving it at the idle stop.I do not have a fuel primer; I pull it through a couple of bladeswith the throttle back at the stop so it will pull fuel throughthe idle circuit (Stromberg carb). It will usually start on thefirst or second blade after I go through the proper motions.Sprinkling the pixie dust works for me ;o)Oscar ZunigaAir Camper NX41CC "Scout"Flying Squirrel N2069Z "Rocket"Medford, OR website at http://www.flysquirrel.net ________________________________________________________________________________