I need help from a Tach Guru!
Thread Starter
Drifting
Joined: Aug 2000
Posts: 1,601
Likes: 52
From: Jefferson City MO
I need help from a Tach Guru!
After the recent threads on tachometer problems, I decided to work on the tach this weekend. What I found is that I do not have a tach filter. After seeing some pictures by SIGNGUY and PAUL67, I might have a wiring problem as well. These pictures are on this thread:
http://forums.corvetteforum.com/zerothread?id=595929
First, from those pictures, there are wires going out of the front of the distributor. These wires led to the tach filter and from what I can tell, go directly to the tachometer board. My wiring is different. The 3 wires going out of the front of the distributor go back into the top of the distributor. Then there are 2 more wires that clip into the Tach port on the distributor and goes to the tach board. I know that the tach board has 3 terminals, but mine only has two wires. Again, there is not a tach filter anywhere. Is this correct?
After seeing this, I decided to take a drive and really watch the tach and see what it is doing. At idle it appears to be accurate, about 750 rpm. When driving casually, it will go up to about 1,100 rpm and stop. When under heavy acceleration, it drops back to 0. Any ideas would be appreciated.
[Modified by Andrew, 8:21 AM 7/14/2003]
http://forums.corvetteforum.com/zerothread?id=595929
First, from those pictures, there are wires going out of the front of the distributor. These wires led to the tach filter and from what I can tell, go directly to the tachometer board. My wiring is different. The 3 wires going out of the front of the distributor go back into the top of the distributor. Then there are 2 more wires that clip into the Tach port on the distributor and goes to the tach board. I know that the tach board has 3 terminals, but mine only has two wires. Again, there is not a tach filter anywhere. Is this correct?
After seeing this, I decided to take a drive and really watch the tach and see what it is doing. At idle it appears to be accurate, about 750 rpm. When driving casually, it will go up to about 1,100 rpm and stop. When under heavy acceleration, it drops back to 0. Any ideas would be appreciated.
[Modified by Andrew, 8:21 AM 7/14/2003]
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Re: I need help from a Tach Guru! (Andrew)
Before tearing into the tach and spending tons of money, do a search on tach filter here, someone posted the factory schematic and parts value for building one....without it, you get all kinds of weird indications....mostly to do with over indicating, and wild fluctuations.....but who's to say??? try the filter fix first, after that, go for the expensive hard stuff.....
Hate to say it, but I think you may have a bad tach head, coil or board...
GENE
Hate to say it, but I think you may have a bad tach head, coil or board...
GENE
Team Owner
Joined: May 2001
Posts: 29,745
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From: Exiled to Richmond, VA - Finally sold my house in Murfreesboro, TN ?? Corner of "Bumf*&k and 'You've got a purdy mouth'."
CI 6-7-8 Veteran
CI-VIII Burnout Champ
St. Jude Donor '06-'10, '13
Re: I need help from a Tach Guru! (Andrew)
From my distributor there are the following wires.
3 in one holder that go into the distributor.
A power wire.
And the tach wire. The tach wire splits right after the clip at the distributor, one wire goes to the tach filter and the other to a male spade terminal. The spade terminal is to hook an external tach for use in setting timing or other diagnostic use.
The wire going to the tach filter then goes through the filter and then off towards the firewall. After that I have no idea where it goes.
3 in one holder that go into the distributor.
A power wire.
And the tach wire. The tach wire splits right after the clip at the distributor, one wire goes to the tach filter and the other to a male spade terminal. The spade terminal is to hook an external tach for use in setting timing or other diagnostic use.
The wire going to the tach filter then goes through the filter and then off towards the firewall. After that I have no idea where it goes.
