new owner
Thread Starter
Racer
Joined: Sep 2008
Posts: 353
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From: West Point MS
new owner
I just purchased a 1975 L48. The car is in pretty good shape except for the usual(weatherstripping). The car has all of its factory components but the tachometer doesn't work. Does anyone know what the problem is or any advice for me on working on this car? This is my first vette and am looking forward to "tinkering" with it.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
I just purchased a 1975 L48. The car is in pretty good shape except for the usual(weatherstripping). The car has all of its factory components but the tachometer doesn't work. Does anyone know what the problem is or any advice for me on working on this car? This is my first vette and am looking forward to "tinkering" with it.
A '75 will have a mechanical tach, which means there is a cable running from the base of the distributor to the tach. Remove that cable from the tach, and see if there is a break in that cable. Maybe connect it to a drill, spin it, and see if the tach responds.
Advanced
Joined: May 2007
Posts: 96
Likes: 1
From: Burgaw North Carolina
If thats not it then most likely the gear is stripped that is in the distributor. Its an easy fix. Zip sells a brass replacement which is what was in the car originally or you can get a stainless gear.
Burning Brakes
Joined: Jun 2004
Posts: 872
Likes: 3
From: Cortlandt Manor New York
If it has a mechanical tach there is a gear in the distributor that drives the cable. The gears usually strip and if you are lucky the distributor gear will still be in good shape. Then it is an easy fix and cheap at about $15 a new distributor main shaft is about $60.
Safety Car
Joined: Feb 2006
Posts: 3,557
Likes: 0
From: Ridgeway VA
I have a '75 and you might need a tachometer circuit board - about $60. This is behind the drivers dash - to take out the drivers dash is a project and has a "lot of while you are there" things to do --- change all lightbulbs, etc. Do fill out your profile! Get the AIM Assembly Instruction Manual to show you how things were put together in 1975, then some good reference books, and vendor catalogs.
PS: In the bottom of the distributor is a HEI ignition module - so if everything electrical all of a sudden cuts off this could be the problem. I found out on a dark night as all lights/electical stopped while I was driving on a country road - almost got crashed into a number of times - so make sure to take a flare/flashlight in your glove box.
PS: In the bottom of the distributor is a HEI ignition module - so if everything electrical all of a sudden cuts off this could be the problem. I found out on a dark night as all lights/electical stopped while I was driving on a country road - almost got crashed into a number of times - so make sure to take a flare/flashlight in your glove box.
Team Owner
Joined: Sep 2006
Posts: 31,160
Likes: 4,236
From: Westminster Maryland
Hi TIMD,
You're in for some big fun!!! A 'New', old car!!!
You said you're going to 'tinker' a little. Having the GM CHASSIS SERVICE MANUAL on hand would be a good idea. You should also have the AIM for your 75 that PETKAH suggested.
Regards,
Alan
You're in for some big fun!!! A 'New', old car!!!
You said you're going to 'tinker' a little. Having the GM CHASSIS SERVICE MANUAL on hand would be a good idea. You should also have the AIM for your 75 that PETKAH suggested.
Regards,
Alan
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Drifting
Joined: Jan 2005
Posts: 1,438
Likes: 3
From: Florissant MO
Two things to check.
1 - the tach filter. A brown wire coming out of the distributor tach side of the HEI.
2 - the tach circuit board behind the tachometer. A real pain to get to.
1975 was the first year using electronic tachs. You can get new tach boards and tach filters at Zip, Mid America, Volunteer Vette and on and on.
1 - the tach filter. A brown wire coming out of the distributor tach side of the HEI.
2 - the tach circuit board behind the tachometer. A real pain to get to.
1975 was the first year using electronic tachs. You can get new tach boards and tach filters at Zip, Mid America, Volunteer Vette and on and on.
Melting Slicks
Joined: Jun 2005
Posts: 2,239
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From: Palatine, Peoples Republic of Illinois
St. Jude Donor '09-'10-'11-12-'13-'14-'15-'16-'17-‘18
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I've read a lot of postings on tach filters on the forum. From what I understand their only function was to reduce the electronic buzz that the distributor causes in the radio. I've been running a '76 electronic tach in my '70 for a couple years now with no filter and no problems.
