It smooths the square signal knocks off the edges...
Tack filter ?
Thread Starter
Race Director
Joined: Jan 2007
Posts: 10,662
Likes: 695
From: Danville Illinois
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Tack filter ?
Doing some tune up stuff and notice that there is no tack filter on my 75.
The tack line goes straight from the dist into the firewall along with the bat wire. Not really sure when or why i removed the filter.
My tack sits at 1700 and doesn't move much, maybe 200 rpms up or down.
Looking at the Willcox tack filter instruction for 75-89 it say the wire can be removed from the filter for testing. My question is what does the tack filter out? static? Is it cleaning up the signal? And would a filter get the tack operating again. Are there any tests i can try with out pulling the tack out?
The tack line goes straight from the dist into the firewall along with the bat wire. Not really sure when or why i removed the filter.
My tack sits at 1700 and doesn't move much, maybe 200 rpms up or down.
Looking at the Willcox tack filter instruction for 75-89 it say the wire can be removed from the filter for testing. My question is what does the tack filter out? static? Is it cleaning up the signal? And would a filter get the tack operating again. Are there any tests i can try with out pulling the tack out?
Last edited by Mod75; Sep 15, 2012 at 08:18 AM. Reason: I dont spell very good
Former Vendor
Joined: Aug 2006
Posts: 76,656
Likes: 1,851
From: Jeffersonville Indiana 812-288-7103
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Burning Brakes
Joined: Jan 2006
Posts: 1,223
Likes: 174
From: Fort Wayne IN
Mine did the same thing. A new board from Willcox did the trick. I added a tach filter too at the time, I did not have one installed before. It isn't too hard of a project, the most time consuming part is getting the column in and out.
See http://www.youtube.com/watch?v=bA3khKLw2Ys
See http://www.youtube.com/watch?v=bA3khKLw2Ys
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Surely there are still copies of the electrical schematic equivalent of that tach filter here or elsewhere online,...easy build if Radio Shack has the parts anymore.....
we used to call them pulse integrators back 30 years ago in the electronic engineering test lab.....doing amazingly similar work to ignitions systems.....been a while....
the configuration is of a PI network....IN/resistor/cap to ground/resistor/another cap to ground, but I forget the values....damnit....
and no way to post it even IF I can find the schematic now....
we used to call them pulse integrators back 30 years ago in the electronic engineering test lab.....doing amazingly similar work to ignitions systems.....been a while....
the configuration is of a PI network....IN/resistor/cap to ground/resistor/another cap to ground, but I forget the values....damnit....
and no way to post it even IF I can find the schematic now....
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Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
With MSD you have to use the MSD box tach output, not the stock one on the HEI.....that is why your tach is acting up.....I don't think you need the filter at that point.....
Instructor
Joined: Mar 2012
Posts: 184
Likes: 0
From: Lancaster Pa
put the msd in yesterday and it ran fine used the two blue springs that brings advance in at 2800 and the 21 degree stop bushing. now tonight get in the car to go for a drive and the tach is jumping around and the engine is pinging and popping out the pipes when you get on it hard it didnt do this last night any advice
