On my trip to and from Minnesota earlier this week, I was having a tough time getting the engine to run as smooth as it usually does when leaned way out past peak. Number 3 cylinder seemed to misfire a bit when I got the red lever far back. Since it had been close to 100 hours since I?d looked at the plugs, and they have close to 500 hours on them anyway, I figured it would be a good idea to have a look the next chance I had. Since there wasn?t much on TV last night (and a hamper of dirty clothes peeking out from the laundry room that I was trying to ignore), I wandered out to the hangar to have a look. Out of curiosity, I decided to watch the clock and see just how log it took to clean and gap the whole set of plugs at a ?normal? pace of work.
The top and bottom cowlings came off in about 5 minutes - I have all stock hinge-pin fasteners, so only have to take off 8 screws at the front of the cowling, and snip a wire tie on the top aft pins to get them off. It?s always nice to see the lower cowl clean and dry inside - no significant oil seeps or leaks!
Grabbing a 3/4? and 7/16? wrench, I had all 8 plug wires disconnected in another couple of minutes - with time out to go wheel the Tailmate to the back end of the plane lower the nose a bit - no use standing on my tip-toes to see over the baffles and reach the top plugs! (Like any Prima Donna, the -8 holds it?s nose pretty high when it?s on the ground?) Another walk to the workbench to grab the spark plug tray, socket, and the torque wrench, and all the plugs are out in another five minutes (Oh yeah, I need that 7/8th inch open end for the top plugs as well- another walk to the tool box). Hmmm?lots of little lead balls in a couple of the plugs (nothing obviously fouled, but usually they are clean as a whistle), and some of the center electrodes are really getting pretty oval - guess I better start shopping for some plugs?.
But, nothing that can?t be cleaned, gapped and flown for now, so over to the work bench for some good lighting and my dental pick to scrape out the deposits down alongside the insulators of the bottom plugs. The upper plugs were clean, so next stop is the little $15 (on sale) cleaner from Harbor Freight, bolt to the side of the vice stand. A minute or so with each plug, a little touch-up scraping with the dental pick, and we?re a half hour into the job. Off with the compressor so I can hear the Mozart on the radio again.
Next stop is the ?fine tool? drawer for the gapper tools. Usually, there isn?t much gap to adjust, but with plugs this ?experienced?, I have to take in a little on each electrode. With the right tools, however, that goes quickly - a stripe of anti-seize on each plug finishes the work at the bench and it is time to go back to the airplane for installation. I swap the plugs around in the tray per my usual rotation scheme and back in the engine they go. It only takes a minute to torque each plug (gotta get the crow?s-foot for the torque wrench to get the tops - baffles are always in the way!), and it is time for plug wires. That done, I stop and pull up a stool. Time for a five minute quiet reflection period as I look over the entire engine compartment for problems.
I fly enough that most of the time, the cowl never comes off between oil changes, so it pays to do a visual inspection whenever I can. Rather than simply look around randomly, I follow each hose from it?s source to it?s end, each wire bundle from the firewall to it?s destination, and each control cable to it?s attach point. I follow the exhaust system from the cylinder to the collectors, looking for tell-tail signs of exhaust leaks. And then a top-down check of the engine compartment for oil leaks - usually, you find a couple of little spots, clean them up, and remember them for next time. I find the usual bit of oil on the mixture cable bracket (I have never found/solved that little seep!), and nothing more. Final checks are to the baffles (for fretting) and the air box for cracks and/or rubbing, and carb heat function). Five minutes well spent, in my book!
Forty five minutes after turning on the hangar lights, it is time of the cowling. Its always a little fiddly to get the baffle seals lined up on the front ramps, but it doesn?t really slow me down - it does remind me, however, that I have to work on those on the ?other airplane? soon. I drop in the vertical hinge pins, secure them with wire ties, and line up the top cowl. More hinge pins, a couple of screws, and the tail comes down - the Valkyrie is ready to roll out the door once again, slightly less than an hour after I began. Gee?.I thought I was going to be able to kill the entire evening in the hangar! Well, maybe I?ll have to go back in the house and do a load of laundry after all?..
The top and bottom cowlings came off in about 5 minutes - I have all stock hinge-pin fasteners, so only have to take off 8 screws at the front of the cowling, and snip a wire tie on the top aft pins to get them off. It?s always nice to see the lower cowl clean and dry inside - no significant oil seeps or leaks!
Grabbing a 3/4? and 7/16? wrench, I had all 8 plug wires disconnected in another couple of minutes - with time out to go wheel the Tailmate to the back end of the plane lower the nose a bit - no use standing on my tip-toes to see over the baffles and reach the top plugs! (Like any Prima Donna, the -8 holds it?s nose pretty high when it?s on the ground?) Another walk to the workbench to grab the spark plug tray, socket, and the torque wrench, and all the plugs are out in another five minutes (Oh yeah, I need that 7/8th inch open end for the top plugs as well- another walk to the tool box). Hmmm?lots of little lead balls in a couple of the plugs (nothing obviously fouled, but usually they are clean as a whistle), and some of the center electrodes are really getting pretty oval - guess I better start shopping for some plugs?.
But, nothing that can?t be cleaned, gapped and flown for now, so over to the work bench for some good lighting and my dental pick to scrape out the deposits down alongside the insulators of the bottom plugs. The upper plugs were clean, so next stop is the little $15 (on sale) cleaner from Harbor Freight, bolt to the side of the vice stand. A minute or so with each plug, a little touch-up scraping with the dental pick, and we?re a half hour into the job. Off with the compressor so I can hear the Mozart on the radio again.
Next stop is the ?fine tool? drawer for the gapper tools. Usually, there isn?t much gap to adjust, but with plugs this ?experienced?, I have to take in a little on each electrode. With the right tools, however, that goes quickly - a stripe of anti-seize on each plug finishes the work at the bench and it is time to go back to the airplane for installation. I swap the plugs around in the tray per my usual rotation scheme and back in the engine they go. It only takes a minute to torque each plug (gotta get the crow?s-foot for the torque wrench to get the tops - baffles are always in the way!), and it is time for plug wires. That done, I stop and pull up a stool. Time for a five minute quiet reflection period as I look over the entire engine compartment for problems.
I fly enough that most of the time, the cowl never comes off between oil changes, so it pays to do a visual inspection whenever I can. Rather than simply look around randomly, I follow each hose from it?s source to it?s end, each wire bundle from the firewall to it?s destination, and each control cable to it?s attach point. I follow the exhaust system from the cylinder to the collectors, looking for tell-tail signs of exhaust leaks. And then a top-down check of the engine compartment for oil leaks - usually, you find a couple of little spots, clean them up, and remember them for next time. I find the usual bit of oil on the mixture cable bracket (I have never found/solved that little seep!), and nothing more. Final checks are to the baffles (for fretting) and the air box for cracks and/or rubbing, and carb heat function). Five minutes well spent, in my book!
Forty five minutes after turning on the hangar lights, it is time of the cowling. Its always a little fiddly to get the baffle seals lined up on the front ramps, but it doesn?t really slow me down - it does remind me, however, that I have to work on those on the ?other airplane? soon. I drop in the vertical hinge pins, secure them with wire ties, and line up the top cowl. More hinge pins, a couple of screws, and the tail comes down - the Valkyrie is ready to roll out the door once again, slightly less than an hour after I began. Gee?.I thought I was going to be able to kill the entire evening in the hangar! Well, maybe I?ll have to go back in the house and do a load of laundry after all?..
