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1redvert
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Joined: June 21, 2004
Posts: 124
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 Posted: Mon Sep 21, 2009 6:30 pm Post subject: 912 tachometer problem |
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hi there, I have a set of 912 porsche gauges that i put in my bug and I am tring to get the tach to work. i think i have hooked it up right and it still don't work. I am using a 7 grand tach with the black face and green numbers, a compufire 45 k coil and a mallory dual points dist. the green wire goes to the tach lead on the coil, hot and ground. is there any thing i am missing, is it a problem with the coil i am using or is it just that the tack is bad? how can i test it to know for sure?
thanks
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TC/TeamEvil
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Joined: February 16, 2004
Posts: 1616
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| Posted: Tue Sep 22, 2009 6:50 am Post subject: |
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| As long as the tach is connected to the negative side of the coil and the tach is 12 volts, you ought to have a signal. Sounds like the tach has broken. |
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1redvert
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Joined: June 21, 2004
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| Posted: Tue Sep 22, 2009 7:24 am Post subject: |
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thats what i was afrade of. i have had it for several years and never tested it. could i use a 911 or 914 tach and just replace the face to make it work? i know they are like 200.00 to have repaired
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Cohibra45
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Joined: March 13, 2005
Posts: 296
Location: Melbourne, Fl
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| Posted: Tue Sep 22, 2009 10:05 am Post subject: |
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| 1redvert wrote: | | thats what i was afrade of. i have had it for several years and never tested it. could i use a 911 or 914 tach and just replace the face to make it work? i know they are like 200.00 to have repaired |
Maybe, the 914, but the 911 is a 8000rpm tach. Contact these people here and get a quote:
http://www.paspeedo.com/porsche.htm
Those old 912 tachs are worth resurrecting. If you don't want to spend the money, just sell it and get the 914 series....... |
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TC/TeamEvil
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Joined: February 16, 2004
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| Posted: Tue Sep 22, 2009 4:40 pm Post subject: |
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"could i use a 911 or 914 tach and just replace the face to make it work?"
Sure you could, the 914 tach mechanism will fit in that case without a problem, even the two little screws that hold the face on will match up.
I use two spoons, with some shirt cardboard under them to protect the face, to remove the needles on the tachs. One on each side, well under the needle spindle NOT just the needle center cover, and they pop right off.
Luck,
TC |
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1redvert
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Joined: June 21, 2004
Posts: 124
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| Posted: Fri Sep 25, 2009 7:42 pm Post subject: |
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i think the first thing i am going to do is take the gauge out and try it with a plain blue coil. i have a feeling that it is the copufire 45 k coil that is the problem with the tach. but thats just my theory. if it dosn't work i will try your idea of swiching the black/green face to another tach. maybe i can find one at pomona. but i havent been there in several years now. What goes bad insid and can they be repaired easly?
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