1979 Monza Tachometer

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1979 Monza Tachometer

Postby Monsterblock » Mon Jun 22, 2015 9:04 am

Hey Guys,
well as the topic says, i got a problem with the tachometer in my 1979 monza. It simply doesnt show any reaction.
I set the needle manually to 0 rpm but as i turn on the ignition it automatically sets it back to about 6 o'clock.
I checked both upper pin slots and there is definetely a difference in volts when i accelerate, so i guess there could be a problem with the tach itself.

If you need some more info, feel free to ask.

Thanks in advance, Martin from germany.
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Re: 1979 Monza Tachometer

Postby cjbiagi » Mon Jun 22, 2015 10:21 am

There is a is tach fiter that is wired into the tach, it's mounted on the intake manifold on a V8 car. I would check that connection and make sure it is tight on the manifold. Sometimes they can be flaky and cause a problem. Otherwise we'll let Spence handle it :D
Clyde.........75 Monza 2+2
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Re: 1979 Monza Tachometer

Postby Monsterblock » Mon Jun 22, 2015 12:34 pm

Now i just need to know where this magical thing is located at. I was looking around the engine but didnt find anything. Maybe i have to remove something to find it.

PS: I got an L4 not a V8 engine.
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Re: 1979 Monza Tachometer

Postby zzip » Tue Jun 23, 2015 10:07 am

Hi Martin,

on the back of the tachometer is a jumper for V6 and V8 .
L4 need NO jumper .

see this forum pls

viewtopic.php?f=44&t=43038

Grtz

Peter from Antwerp
1988 Monza L4 2.5L
1989 Monza Spyder L4 2.5L
1990 Monza Spyder V6 3.2L
1991 Monza Spyder V6 3.8L
2013 Monza V6 3.8L
2014 Starfire V6 3.8L
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Re: 1979 Monza Tachometer

Postby Monsterblock » Tue Jun 23, 2015 11:01 am

Hey Peter,
Thanks for the answer but the back is clean.
There is also no change in Volts when i checked the pins where the tach is plugged in
while i am accelerating, so it also could be a problem with the source.
My father will check the tach instrument itself if there are any issues.
If not then i have to search elsewhere for the problem.
Still i didnt find the filter yet. I will take a picture maybe someone can help me identfy it :D.

Thanks in advance.
Martin from germany.

PS:
Image

Image
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Re: 1979 Monza Tachometer

Postby zzip » Tue Jun 23, 2015 1:10 pm

Ok Martin,

good luck

Peter from Antwerp
1988 Monza L4 2.5L
1989 Monza Spyder L4 2.5L
1990 Monza Spyder V6 3.2L
1991 Monza Spyder V6 3.8L
2013 Monza V6 3.8L
2014 Starfire V6 3.8L
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Re: 1979 Monza Tachometer

Postby cjbiagi » Tue Jun 23, 2015 1:21 pm

That capacitor you have shown on the firewall in the second pic does look like the tach filter. I believe it needs to be grounded through the mounting tab so make sure that is clean and making a good connection.
Clyde.........75 Monza 2+2
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Re: 1979 Monza Tachometer

Postby spencerforhire » Wed Jun 24, 2015 6:18 am

When checking for voltage on the tach feed wire with a multi meter, remember you're looking for AC, not DC. Should be pretty easy to tell if the problem is under the hood or with the tach itself. The voltage doesn't vary a lot with RPM, but should be somewhere between 4 and 8 v. with the engine running.
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72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
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Re: 1979 Monza Tachometer

Postby Monsterblock » Wed Jun 24, 2015 12:10 pm

Thanks for the answer spencer,
i checked the wire and also the plugs where the tach is plugged in and the result was 4,5 - 9 V depending on the rpm.
Still the only reaction of the tach after i set it manually to 0 rpm is going back to about a 6 o'clock setting.

If i would look for a "new" tach, where would be the highest chances for me to get one?
Are the even aftermarket versions which would work?

Thanks in advance,
Martin from Germany
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Re: 1979 Monza Tachometer

Postby jim327monza » Wed Jun 24, 2015 6:49 pm

Martin, I have a NOS tach for the 76 monza. If Spencer or someone else can tell tell us if it will fit, we can work something out. Box is marked 9.750 5658706 76h. w/ gauges. Circuit board is marked 4-6-8 cyl 58588706 9165 Hope this will help you.
Jim H.
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Re: 1979 Monza Tachometer

Postby Monsterblock » Thu Jun 25, 2015 3:23 am

Hey Jim,
that would be great if it would fit. Still needs approval, but i'm already glad for your help.

Martin
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Re: 1979 Monza Tachometer

Postby spencerforhire » Thu Jun 25, 2015 6:49 am

To the best of my knowledge, all Monza(and clones) tachs should fit from 1976-1980. I don't even know if there were different faces that showed different redlines.
The "fleet"-
77 Vega Estate wagon- project(someday)will have TPI305/T-5, S-10 spindles/axles
72 Vega HB Drag Car -383/'Glide/9"(9.35@146.19)(5.94@117.28 1/8th)
76 Vega GT- 400/4spd/9" retired from active duty(rusty)
03 Silverado 2WD ex.cab (work truck/parts hauler)
04 Silverado 2WD ex.cab (retired)
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- spare
and 3 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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