Tach filter revisited
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From: San Diego - Deep Within The State of CONFUSION!
Tach filter revisited
Hope this topic hasn't been worn out. :smash: I finally got a chance to look at my '76 Vette's tach filter...anticipating making one as per the schematic I found somewhere on this forum.
When I looked at the schematic, it showed an IN and an OUT then a ground. Looking at what is on my car, is just a round cylinder shaped deal with a single lead .. and there is just one connector in the harness that goes to it. :yesnod:
I have a reasonable amount of techie experience :blueangel: and I've used a soldering iron a few hundred times but what the heck am I missing here???? :confused: :mad :confused: :mad :confused:
When I looked at the schematic, it showed an IN and an OUT then a ground. Looking at what is on my car, is just a round cylinder shaped deal with a single lead .. and there is just one connector in the harness that goes to it. :yesnod:
I have a reasonable amount of techie experience :blueangel: and I've used a soldering iron a few hundred times but what the heck am I missing here???? :confused: :mad :confused: :mad :confused:
Melting Slicks
Joined: May 2002
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From: Wisconsin
Re: Tach filter revisited (SanDiegoPaul)
Yeah, I need one of them also, but it can wait. My tach isn't too jumpy. I don't need exact tach readout. Bouncing from 5500rpm to 6000rpm isn't that big of a deal. If I did it though, I'd probably make my own IC and stick it in a plastic box.
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Re: Tach filter revisited (SanDiegoPaul)
Paul,
It sounds like you are describing a RF noise filter capacitor. They look a lot like the old condenser/capacitor that was in points type ignition systems. On the earlier C-3's there were several of them on the car to cut down on electrical interference (mainly AM) on the radio. There is one on the heater/AC blower as well as the ignition.
Paul's picture really shows what a factory correct tachfilter should look like.
It sounds like you are describing a RF noise filter capacitor. They look a lot like the old condenser/capacitor that was in points type ignition systems. On the earlier C-3's there were several of them on the car to cut down on electrical interference (mainly AM) on the radio. There is one on the heater/AC blower as well as the ignition.
Paul's picture really shows what a factory correct tachfilter should look like.
Team Owner
Joined: Aug 1999
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From: Ontario
Re: Tach filter revisited (Smokehouse69)
I guess that I am lucky that mine is still working. I did a parts search at work on those units. They are GM-discontinued, of course, but they were not just a Corvette item. They appeared on all mid-to-late 1970s GM vehicles with HEI and a tach. So check the the salvage yards for Camaros, Firebirds, etc.
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From: San Diego - Deep Within The State of CONFUSION!
Re: Tach filter revisited (paul79)
I looked at mine closer and it does have two leads ... my bad! But neither of them go to the tach connection on the HEI. Rearranging the wiring didn't change things a single bit.
The tach still hovers at 1250RPM day or night rain or shine. It does however, quiver when I turn the key on or shut off. :smash: :smash:
The tach still hovers at 1250RPM day or night rain or shine. It does however, quiver when I turn the key on or shut off. :smash: :smash:
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From: San Diego - Deep Within The State of CONFUSION!
Re: Tach filter revisited (paul79)
I agree. If the tach is stuck, it is not the filter.
Problem is, that it doesn't LOOK LIKE the tach gauge is stuck! It moves a bit when the key is turned on. And the way it bounces, it looks free not stuck or sticking.
I KNOW what it REALLY is though: Frustrating! :smash: :smash: :seeya
Problem is, that it doesn't LOOK LIKE the tach gauge is stuck! It moves a bit when the key is turned on. And the way it bounces, it looks free not stuck or sticking.
I KNOW what it REALLY is though: Frustrating! :smash: :smash: :seeya
