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sunbird tach mod by vette7584
Started on: 12-15-2014 10:45 AM
Replies: 2 (170 views)
Last post by: Irrationable on 12-15-2014 01:28 PM
vette7584
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From: schaghticoke ny usa
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Report this Post12-15-2014 10:45 AM Click Here to See the Profile for vette7584Click Here to Email vette7584Send a Private Message to vette7584Edit/Delete MessageReply w/QuoteDirect Link to This Post
can anyone help, please? i want to install the sunbird tach into my 1988 with 3800sc. what i need to know is what i need to modify the tach. i have seen threads that say 1meg ohm trimmer pot, well i went to the local radio shack and bought what i thought was the right part, was told its not. thats fine, i do not know or pretend to know anything about electronics. i have looked on a website for a place called frys, well, theres thousands of listings, so what i am asking is can anyone just please give me a part number on the part they used? i would really appreciate it. thanks
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Irrationable
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Report this Post12-15-2014 01:22 PM Click Here to See the Profile for IrrationableSend a Private Message to IrrationableEdit/Delete MessageReply w/QuoteDirect Link to This Post
I JUST finished installing a sunbird tach myself. The resistance needed to properly calibrate the tach is around 200,000 ohms, or 200kohms. A variable resistance trimmer aka potentiometer is needed to fine tune this resistance so that your tachometer reads exactly as it should.

1 meg ohm is equal to 1,000,000 ohms. So, a 1 meg trimmer can be adjusted from 0 to 1million ohms. Basically, you need any trimmer that exceeds 200k.

For my tach, I ordered this trimmer assortment off of ebay. Both the 1meg and 500k timmers in this assortment will fit your needs. I opted to use the 500k as it gave me a greater degree of adjustment to fine tune my tach readout. Each trimmer has 25 turns between full resistance and zero resistance, the closer the resistance is to what you need, the greater degree of adjustment you'll get for each turn of the screw on the trimmer.

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"The Twins"
'87 GT 3.4 pushrod daily driver
'88 GT 3.4 DOHC swap in progress

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Irrationable
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Report this Post12-15-2014 01:28 PM Click Here to See the Profile for IrrationableSend a Private Message to IrrationableEdit/Delete MessageReply w/QuoteDirect Link to This Post
This is the how-to guide here on the forums that I used to install my tachometer. http://www.fiero.nl/forum/A...130314-2-110302.html

Also, a helpful tip that I learned the hard way: when you solder the leads to your trimmer. solder them to the FIRST and SECOND pins of the trimmer. If you use the first and third pins, you get full resistance with no adjustment. It took me almost an hour to realize what I had done wrong when I was installing mine.

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"The Twins"
'87 GT 3.4 pushrod daily driver
'88 GT 3.4 DOHC swap in progress

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