rpm pickup

[ramachandra]

I am using Lycoming O-235 on Long EZ. I want to take engine rpm pick up from the slick magneto instead of using mechanical tacho generator. My analogue engine rpm gauge has a 5 pin plug. Could some one please let me know how to connect it with the magneto. Magneto has two hexagonal nuts with six holes in each. Is it for any electrical connection or only for cooling.

                         Thanks for the help.

                              Regards
                                                          Ramachandra

[Anonymous]

Venting

[Waiter]

Dah :?      I was trying to picture what Ramachandra was describing, Of course the vent plugs!!!

I think there's only two ways you can get a tach signal from the Mag, P-Lead or Spark plug.

There are a couple inexpensive Tach's (WestTech) that run off your P-Lead,  but they do leave a little to be desired as far as accuracy. I think  some of the newer electronic guages can also read the P-Lead with good accuracy. There was a post here not long ago "StratoMaster" or something like that.

Good Luck

Waiter

[one guest]

Like everyone said the six holes are the vent holes.   your  P  lead should go to the number 2 pin on your rpm gauge and the number 5 pin on your gauge should go to the aircraft ground.

[easyrider]

I am running a Jeff Rose Tach with Jeff Rose Electronic on the bottom plugs and Slick impulse on the top. The Tach runs fine. It is also accurate, I ran the original mechanical tach in parallel for several hours and the readings were the same.
Easyrider

[hewlett]

Attaching ANYTHING to P Leads can cause problems.  Accidental grounding kills the mag.

[ramachandra]

thanks for all those replies. I tried to use handheld electronic tachometer near sparkplugs. The display was nil. From the suggestion regarding connecting tachometer, I understood that the cable going from magneto to rotory switch (in cockpit) which switches the magneto ON & OFF, is to be tapped and connected to the tachometer pin no.2 and the ground of magneto and pin no 5 of the tachometer are to be connected to A/C ground. Am I right ? Is there any restriction on the magneto to be used for rpm pickup ? i.e. left or right etc. What about connections to other pins of the tachometer? So many doubts!

                                                            thanks
                                                          Ramachandra

[Gilbert DRIEUX]

Have alook at :
Aircraft Spruce  /  Westach Tachometers

http://www.aircraftspruce.com/catalog/inpages/west2tachs.php

    >>> bottom of page<<<

I use this system. Sender is connected to tachometer dysplay by wires from sender at engine tach drive.
No mag risks.

Regards.

>>
 REMOTE HEAD TACHOMETER
Complete kit
 P/N K2GA3-1/2A $124.95

Sender only
 P/N 303-DGT $41.90

Tang only
 P/N 444-2 $3.30
 
This tachometer is driven with power supplied by a transducer on the engine tach drive. Range 0-3500 RPM. Wt. 6 oz. Includes Gauge, sender, and tang.