Tach filter...A work in progress?
Thread Starter
Instructor
Joined: Jun 2004
Posts: 249
Likes: 0
From: clinton ut
Tach filter...A work in progress?
The tach filter seems to be a big problem and replacement a rip-off if you can even find one! I checked mine with a Sencore LC 103 capacitance/inductance tester and found it to be 0.089 micro-farads. A common value is 0.10 micro-farads at 20% tolerance. Mine is 16 years old so meets specs for me! My tach works just fine. The capacitor (filter) is also grounded through the case by the mounting tab. Mine has not been grounded for 1 1/2 years. No problems. I re-located mine this weekend and grounded it. I accidentally bought a 1.0 micro-farad in stead of a 0.1 at Radio Shack but physical dimension should be the same for each of them. I installed the 1.0 to see what would happen...Works ok. I will run it a few days to be sure, then I will install the correct 0.1 capacitor from Radio Shack. Included are pics of the original (re-located) and the size comparison to the Radio Shack one. On Sunday I plan to capture some data with an oscilloscope so we can ALL see the signal with 3 different caps and with no cap. Yes, I have no life.
Thread Starter
Instructor
Joined: Jun 2004
Posts: 249
Likes: 0
From: clinton ut
Usually my philosophy too.
You are correct. I started this one awhile ago when my tach started jumping all over the place. Cleaning the connector to the distributor had no effect so I removed it from the engine and isolated the ground and lo and behold...it started working just fine. I recently decided to re-mount it elsewhere and with all the recent tach threads I figured what the heck, I think I will experiment. Maybe my original problem was heat related? It works fine grounded now so that wasn't it.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
I had a wire break off one end, years ago. I simply took the wire to the filter and plugged it into the distributor cap, eliminating the filter. The tach hasn't missed a beat since.
RACE ON!!!
RACE ON!!!
