BryanLight Posted January 4, 2018 Report Posted January 4, 2018 Hey guys, time to toss a new tach and cable in. '61C. Can anyone help me with part #s? I'm a bit confused on aircraft spruce, as the recommended tach is calibrated for 2300rpm cruise. I run 2500 all the time, so wouldnt i want the 2566? Also a seemingly obvious question.. i assume clockwise, correct? I just want to get a mechanical replacement in there, am not interested in electronic. and cable length? Thank you! Quote
TTaylor Posted January 4, 2018 Report Posted January 4, 2018 I know you want the mechanical tach, but it is time to come out of the dark ages and use a simple electronic one. Cost difference is almost nothing after you get the mechanical tach and cable. The EI is so much better, gives you total time of flight, tach time, and digital rpm reading. As to the original question. The 2300 assumes you have a mix of cruise and lower rpm operations. This averages out to about 2300 rpm. Again a nice reason to use an electronic that only counts time when you are above 1800 rpm. Quote
Hank Posted January 5, 2018 Report Posted January 5, 2018 7 hours ago, TTaylor said: I know you want the mechanical tach, but it is time to come out of the dark ages and use a simple electronic one. Cost difference is almost nothing after you get the mechanical tach and cable. The EI is so much better, gives you total time of flight, tach time, and digital rpm reading. As to the original question. The 2300 assumes you have a mix of cruise and lower rpm operations. This averages out to about 2300 rpm. Again a nice reason to use an electronic that only counts time when you are above 1800 rpm. It's easier and faster to glance at a needle and tell that it's in the right place compared to looking at a digital LCD and reading the number. Then add in turbulence, when that little number on the far side of the panel is bouncing up and down. No thanks, I'll keep the one that is easier for me to use. Here in the 21st Century, it's called HMI (Human Machine Interface). For me, needles are much better tha digital display, even with the red & green LEDs in 100 RPM increments. Quote
Bob_Belville Posted January 5, 2018 Report Posted January 5, 2018 13 minutes ago, Hank said: It's easier and faster to glance at a needle and tell that it's in the right place compared to looking at a digital LCD and reading the number. Then add in turbulence, when that little number on the far side of the panel is bouncing up and down. No thanks, I'll keep the one that is easier for me to use. Here in the 21st Century, it's called HMI (Human Machine Interface). For me, needles are much better tha digital display, even with the red & green LEDs in 100 RPM increments. Hank, Electronic does not mean digital display only. And it need not be small or out on the right wing. The mechanical tachs are much more likely to be inaccurate, aren't they? Furthermore, a tach is not an ASI or a VSI, or an altimeter for which one might argue the need for HMI considerations. There's no need to be adjusting the prop control on the basis of a glance and immediate recognition as we do the elevator in reaction to changes in speed, vertical speed, and altitude. Quote
carusoam Posted January 6, 2018 Report Posted January 6, 2018 M20C part number can be found in the parts manual. Somebody recently posted that piece of golden jewelry around here somewhere... My 65C's tach had part number 660011 1 printed on it. Its markings changed over the years. So even the originals needed to be updated along the way. Somebody added a piece of tape to the front of mine. Artistic, but not acurate... think parallax to get a feel for it... As for cable length... it goes from the back of the engine to the back of the instrument panel. Don't get anything too long or too short. What happened to the one that was in the plane that you can't duplicate what is there? the back of my tach is marked with an arrow. Turning the center drive mechanism in the direction of the arrow, I can generate about 500rpm.... the arrow on the back indicates counter clockwise. Even though the needle on the front moves clockwise when increasing rpm... If it’s not too much trouble, I’d copy what Bob has. His digital device has both a digital numerical display and a digital needle. I just noticed the fancy display having both, only a few days ago. My M20C's tach is a desk ornament now. At 4,290 hours it decided to throw it's needle. It got a new cable. The replacement probably came from eBay or someplace like that... the new cable probably was sourced from A Spruce. Delivered to my mechanic for installation details... Best regards, -a- Quote
kerry Posted January 6, 2018 Report Posted January 6, 2018 Do not get the tach cable from aircraft spruce. It's made by ACS and it will not work. You can send your tach cable to a speed shop and have a new one made up to match your original cable. Quote
RobertGary1 Posted January 9, 2018 Report Posted January 9, 2018 I fly both mechanical and digital tachs. I far prefer the mechanical steam gauge tach for the same reason car manufactures still mostly prefer steam gauges. You get more at a glance with a precision needle than a digital display. -Robert Quote
RLCarter Posted January 10, 2018 Report Posted January 10, 2018 On January 6, 2018 at 1:02 AM, kerry said: Do not get the tach cable from aircraft spruce. It's made by ACS and it will not work. You can send your tach cable to a speed shop and have a new one made up to match your original cable. Why do you say that? I know of 2 different C's that have Spruce cables on them for the past several years Quote
kerry Posted January 10, 2018 Report Posted January 10, 2018 1 hour ago, RLCarter said: Why do you say that? I know of 2 different C's that have Spruce cables on them for the past several years They got luckier then me. I tried 2 different spruce cables and neither worked. I searched it online and found other Lycoming airplanes having the same problem I did with the spruce cable. Some said they could modify the spruce cable to work. Trying to modify it didn't work for me. I sent my old cable to a speed shop in Texas and they made me a new one. The speed shop cable looked better quality to me and it works fine. Quote
RLCarter Posted January 10, 2018 Report Posted January 10, 2018 7 minutes ago, kerry said: They got luckier then me. I tried 2 different spruce cables and neither worked. I searched it online and found other Lycoming airplanes having the same problem I did with the spruce cable. Some said they could modify the spruce cable to work. Trying to modify it didn't work for me. I sent my old cable to a speed shop in Texas and they made me a new one. The speed shop cable looked better quality to me and it works fine. They wouldn't go in the tach drive? Both of the ones I know of were ordered about 4 years ago, seem to remember that the Spruce cable was an inch or 2 longer but other than that they went right on Quote
kerry Posted January 10, 2018 Report Posted January 10, 2018 3 minutes ago, RLCarter said: They wouldn't go in the tach drive? Both of the ones I know of were ordered about 4 years ago, seem to remember that the Spruce cable was an inch or 2 longer but other than that they went right on If I remember correctly the cable core was to short for the cable housing and wouldn't engage the tach. I could see my existing cable core was a little longer when I matched up the ferrules. 1 Quote
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