Guages

[Wayne Pearce]

I have two problems on '73 G norm, wonder if anybody can help.

Problem A. left hand, front tacho needle fluctuates, figure it could be either breaker points, suppressor or guage so my question really is how often do the breaker points need adjustment, mine have'nt been done in long long time ?

Problem B. can't calibrate rear EGT needle high enough peaks a bit under half scale. I reckon it is a mechanical thing with the adjusting knob on face of guage, will I have access to this if I remove face of guage and are there any tricks I should be aware of.

Other than that I just flew from bottom of Australia to top of Australia and back again and you can bet I would'nt do it in any other machine, trouble is after about 4 hours bum is numb, so I am amazed at the patience and tough bums of those who fly with flint tanks etc.

Best regards to all, Wayne

[Jerry De Santis]

Hello wayne,

One easy way to tell if its the gauge is to switch the connections between the left and right gauges. Start the front engine and see how the gauge behaves on the right side. If it is smooth, it is the gauge that is the problem.
Cheers
Jerry

[Mark Hislop]

Wayne:

Your problem might be as simple as a loose connection. There are two wires leading from the mag. There is a quick disconnect spade type lug on each wire that connects to the wiring harness that leads to the tach. I had the same symptoms as you did on my rear engine, and my problem was that one of the conductors had broken inside of the insulation right near the connector, thus making a poor, intermittant contact. Crimping on a new connector cured the problem. I also had the same symptoms a year later on my front engine. The connector on one wire was not very tight. Recrimping again cured the problem.

Mark

[Bob Cook]

Wayne

I do 5 hr flights on a regular basis. Sheep skin covers helps the numbing problem. Sure you have some of these down there <G>

re tack.

The tack is driven off the right tack points on the mags. Your points are getting dirty and should be cleaned and checked. There is also a SB out on the mags for a 500 hr check.

Re Alcor EGT. There is a screwdriver adjustment on the front that can be used to "calibrate" the guage. These are simple junction probes that generate a small voltage based on heat. If you are getting a reading then I would suspect the probe is okay. You can always swap the probes (per larry) to see if it is the probe. I have a guage and probes if you need them..

fyi

bob

[Guy Paris]

I believe the 500 hr. inspection, re: 96-12-07 is an Airworthiness Directive, (A D).... Guy, old72driver....