---------------------------------------------------------- M14PEngines-List Digest Archive --- Total Messages Posted Tue 01/20/09: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:55 AM - Re: Tachometer (Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E) ________________________________ Message 1 _____________________________________ Time: 09:55:30 AM PST US Subject: RE: M14PEngines-List: Tachometer From: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" I agree with George that there is always risk involved when you start messing around with P Leads and connecting anything to them. If not done with careful design and proper caution, hooking anything (else) to the P Leads can also easily result in a massive increase in radio noise as well. That said, this model: HORIZON INSTRUMENTS MODEL P-1000 TACH has worked extremely well in at least five M-14 equipped aircraft that I am aware of, and allows you to totally remove the mechanical TACH TRANSMITTER that attaches to the engine, which in my experiece tends to have a rather poor track record for long term reliability. The P-1000 Tach also gives you a safety BENEFIT in that it will instantly tell you if you have a failed mag. I mean really... How many of us fly along and check the mags while airborne? This device will give you an immediate indication of a mag failure, which is a lot better than finding that out just before taking off when doing your usual mag check. In addition, it has engine overspeed LED's that will alert you should your engine go over a certain "limit" speed. And, it also includes engine time recording, etc., etc. This model includes an internal opto-isolator design that makes the possibily of it causing a mag failure to be extremely remote, although of course nothing is impossible. Here is a place to read about it. Out of all the "P Lead" tachs, this is the only one I would recommend. Be advised of one big point though... In every case where someone else installed one of these things on their own aircraft, there has been a very real and noticable increase in "P Lead" induced radio noise. I have had to go back and rip out poor wiring, and use high quality shielded wire and proper lead bonding and grounding to deal with this, so it is best the wiring of this device to an A&P or otherwise highly qualified Avionics type of guy. STRONG emphasis on this. http://www.aircraftspruce.com/catalog/inpages/p1000digitaltach.php Mark Bitterlich N50YK -----Original Message----- From: owner-m14pengines-list-server@matronics.com [mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of George Coy Sent: Monday, January 19, 2009 8:49 AM Subject: RE: M14PEngines-List: Tachometer Mechanical tachs generally work on the speed of the camshaft. That is 50% of the crankshaft speed. The only place that the cam speed is available to drive a tachometer on the M14 is at the center of the air start. The magneto rotor is the only other part that rotates at 50% of the crankshaft speed. There are many tachometers that run from magneto electrical pick up will also work. Be wary of the ones that actually connect to the "p" lead as a tachometer failure could result in a magneto failure. You could also have your Russian tachometer face remarked to actual RPM instead of % RPM. George Coy Coy Aircraft Sales 714 Airport Rd. Swanton VT 05488 802-868-5633 off 802-363-5782 cell george.coy@gmail.com SKYPE george.coy -----Original Message----- From: owner-m14pengines-list-server@matronics.com [mailto:owner-m14pengines-list-server@matronics.com] On Behalf Of HBaker Sent: Sunday, January 18, 2009 5:31 PM Subject: M14PEngines-List: Tachometer --> Is there a mechanical tachometer out there that is not in % of rpm that I can put on the M14P, and does it install in the center of the air start? -------- Currently building a Murphy Moose - any help would be appreciated. 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