1976 Vega Tachometer Issue

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1976 Vega Tachometer Issue

Postby jumpnjoe59 » Fri Jan 28, 2011 9:23 pm

Recently purchased a stock 1976 Vega GT. The factory tachometer jumps straight to 6,000 RPM (give or take) as soon as the car is started. Doesn't really change if the car is idling or if it is being revved. Has anyone seen this before? Any ideas on a fix? Is there a web site where I can purchase a GM repair manual. Not looking for an owners manual but the repair manual. Thanks in advance.
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Re: 1976 Vega Tachometer Issue

Postby cjbiagi » Sat Jan 29, 2011 1:36 pm

Sounds like possibly a wiring issue or maybe the tach filter. Usually when a electric gauge swings to one side it is not getting the signal voltage. Usually there are 3 wires, constant 12 volts, a ground, and the signal voltage. I'll try and look at the schematic later...............
Clyde.........75 Monza 2+2
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Re: 1976 Vega Tachometer Issue

Postby jumpnjoe59 » Thu Mar 24, 2011 12:42 pm

Thanks for the reply...I don't believe it is a wire issue as I have traced most of that out. Not sure what the tach filter is so that may be it. It appears to be within the tach itself. I may find an after market tach and try to put it in place of the stock tach but would love to keep a factory tach. The clock wasn't working so it was replaced with an oil gauge. That provides better data for me than a clock anyway!
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Re: 1976 Vega Tachometer Issue

Postby spencerforhire » Thu Mar 24, 2011 9:42 pm

One of our members (Tim McCabe) rebuilds and re-calibrates tachometers; send him a P.M. on his profile- memberlist.php?mode=viewprofile&u=112
The "fleet"-
77 Vega Estate wagon- project will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.45@146.19)(6.01@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
04 Silverado 2WD ex.cab (work truck/parts hauler)
06 Haulin' 20ft enclosed car transporter
93 Suburban- 350/4L60(retired)
00 Saturn SW2- wife's car
01 Saturn SC2- younger son's project
00 Saturn SL2- daughter's car
98 Saturn SW2- older son's ride
99 Saturn SW2- spare
and 2 more Saturn "parts cars"
Note- the very act of listing all of these has made me realize I have some kind of problem.....

Visit http://www.spencerforhire.ca
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1972 Chevrolet Vega Hatchback

Re: 1976 Vega Tachometer Issue

Postby cjbiagi » Thu Mar 24, 2011 10:45 pm

This is what a tach filter looks like. Most all gauges have 3 wires to make them work, a ground wire, a full time 12 volt wire and a "signal" wire from a sender of some sort. In this case it would be coming from the distributor. The signal wire from the distributor runs through a tach filter that looks similar to this. It's usually mounted on the intake manifold or accelerator bracket on a V8, not exactly sure where it is on a 4 cylinder. This particular capacitor is for a heater blower motor but is looks very close.
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Clyde.........75 Monza 2+2
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