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Recently activated the advanced timing for Surefly in my PA32-300 (previously was installed but fixed timing DIP switches set). A couple of issues arose:
1- install instructions assume the advanced timing DIP will be set at initial install and setting TDC of the mag. If you do the initial install without the DIP switch settings for advanced timing, any subsequent DIP switch change requires re-energizing the timing lead for the Surefly unit to recognize the DIP switch change. Just making the change won't work.
2- Install recommends lock-tite on the screw cover over the DIP switches, but this makes it impossible to remove the cover to change any settings without removing the Surefly first.
Inflight-
1- I have heard and can confirm the advanced timing will increase CHTs substantially. I was assuming this would allow you to reduce power settings since the increased CHT would imply more power for a given fuel setting. Originally I was able to get 145ktas on 15.5-16GPH (80deg ROP) at 7-8k ft. My hottest (#6) would be right at 360 deg, while my coolest (#1) would be 310 or so. I could go LOP but lose 7-10kt doing this. With advanced timing, I am seeing 405deg on #6 during climbout. At 80deg ROP am able to get 144ktas but #6 is 400-405deg (too hot for me) and coolest is at 330deg. #2 (2nd hottest is about 380) Only way I can get hottest cylinders <400 is with 17GPH but I don't see any increased speed with this, if anything maybe 2-3kt slower. Also, ends up about 150ROP on EGTs (although all pretty even across the board). I can go LOP better- down to 12.1-12.4GPH at 20LOP (richest, #2) and CHTs are all 315-250 but speed suffers- only 135KTAS. I was under the assumption that advanced timing would improve combustion events (at the expense of increased CHT, but with lower fuel burn for a given power setting).
Recent Mike Busch article recommended keeping CHT 350-400 to minimize lead bromide contamination of valve stems and valve sticking. I know Lycoming can go hotter but have always heard better to keep CHT <400, preferably in the 360 range.
1- install instructions assume the advanced timing DIP will be set at initial install and setting TDC of the mag. If you do the initial install without the DIP switch settings for advanced timing, any subsequent DIP switch change requires re-energizing the timing lead for the Surefly unit to recognize the DIP switch change. Just making the change won't work.
2- Install recommends lock-tite on the screw cover over the DIP switches, but this makes it impossible to remove the cover to change any settings without removing the Surefly first.
Inflight-
1- I have heard and can confirm the advanced timing will increase CHTs substantially. I was assuming this would allow you to reduce power settings since the increased CHT would imply more power for a given fuel setting. Originally I was able to get 145ktas on 15.5-16GPH (80deg ROP) at 7-8k ft. My hottest (#6) would be right at 360 deg, while my coolest (#1) would be 310 or so. I could go LOP but lose 7-10kt doing this. With advanced timing, I am seeing 405deg on #6 during climbout. At 80deg ROP am able to get 144ktas but #6 is 400-405deg (too hot for me) and coolest is at 330deg. #2 (2nd hottest is about 380) Only way I can get hottest cylinders <400 is with 17GPH but I don't see any increased speed with this, if anything maybe 2-3kt slower. Also, ends up about 150ROP on EGTs (although all pretty even across the board). I can go LOP better- down to 12.1-12.4GPH at 20LOP (richest, #2) and CHTs are all 315-250 but speed suffers- only 135KTAS. I was under the assumption that advanced timing would improve combustion events (at the expense of increased CHT, but with lower fuel burn for a given power setting).
Recent Mike Busch article recommended keeping CHT 350-400 to minimize lead bromide contamination of valve stems and valve sticking. I know Lycoming can go hotter but have always heard better to keep CHT <400, preferably in the 360 range.
