Tach not working
Thread Starter
Burning Brakes
Joined: Dec 2005
Posts: 1,179
Likes: 100
From: cranford nj
Tach not working
Ok guys here is story. 71 350 4sp mech tach installed new gear and the needle bounced now it doesn't move.The cable is free and does not seem to be broken.
Tech Contributor
Joined: Aug 1999
Posts: 15,173
Likes: 3,982
From: Connecticut, USA
Did you replace the main shaft in addition to the gear? Also the replacement gears on the market now are,hum what that's word....junk. Sorry but most of the ones I used were really not machined correctly, I had to return them. They bound up by hand,engine power would have stripped them in 30 seconds. You're going to have to pull the distirbutor and take a look at what you have going on there.
Racer
Joined: Jul 2001
Posts: 363
Likes: 0
From: Winston-Salem NC
There is a cross gear inside the distrbutor where the tach cable screws into the side of the distributor. This gear meshes with teeth on the main distributor shaft. The teeth are probably stripped on the cross gear, and possibly on the main shaft as well. 
Been there, done that!
Jeff
Been there, done that!
Jeff
Le Mans Master
Joined: Oct 2005
Posts: 6,247
Likes: 471
From: Glen Allen, VA
Can you chuck up the cable in a drill and see if the tach works? I've done that to diagnose speedo cable problems, but I've never had a cable drive tach, so I don't know, but maybe that can help you track the problem.
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Originally Posted by C3 4ME
Can you chuck up the cable in a drill and see if the tach works? I've done that to diagnose speedo cable problems, but I've never had a cable drive tach, so I don't know, but maybe that can help you track the problem.
Yes ...HOWEVER ... run the drill in REVERSE for tach drive ... pull cable out of distributor & Gently chuck cable's core into drill motor ... spin drill in REVERSE ... if drill is running 600rpm ... the tach should read about twice that ... 1200rpm.
Instructor
Joined: Apr 2005
Posts: 203
Likes: 20
From: Madison Indiana
I just had the same problem today in my '69. Tach was working, now it's not.
This post was helpful. I pulled the cable and spun it and the tach wants to move, so I assume the problem is in the distributor.
What part(s) do I need and how do I do it once and correctly? Any help would be appreciated.
Thanks!
This post was helpful. I pulled the cable and spun it and the tach wants to move, so I assume the problem is in the distributor.
What part(s) do I need and how do I do it once and correctly? Any help would be appreciated.
Thanks!
Last edited by Allen_396; Mar 20, 2006 at 08:29 PM.
Safety Car
Joined: Jun 2002
Posts: 4,135
Likes: 1
is the thrust washer in? it keeps the side gear meshing correctly with the drive,the cut of the gear makes the side gear force outward,,against the thrust washer,,no thrust washer,,drive and or side gear wipes out....4 dollar part
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Instructor
Joined: Apr 2005
Posts: 203
Likes: 20
From: Madison Indiana
Originally Posted by carl a
is the thrust washer in? it keeps the side gear meshing correctly with the drive,the cut of the gear makes the side gear force outward,,against the thrust washer,,no thrust washer,,drive and or side gear wipes out....4 dollar part
Thanks!
Allen
