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Registered
Join Date: Jun 2001
Posts: 35
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Tachometer
I have a bouncing tachometer in a '69 912 which I can't figure out. Here are the symptoms.
1) Tach works fine when coasting (clutch is in) or in neutral at any RPM. 2) Tach bounces when in gear after 3000 rpm and gets really bad around 4000 rpm. Generally this gear has to above 2nd. Ideas? Dave |
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11-10-2001, 05:30 PM
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Join Date: Jan 2001
Location: KS
Posts: 708
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Must be the sensor on the engine as its all electronic.
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11-10-2001, 08:48 PM
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Senior Member
Join Date: Nov 2000
Location: Stuttgart FRG
Posts: 2,307
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Hello
Check your condensator on the breaker contact or just renew it. Grüsse |
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11-11-2001, 01:05 AM
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Registered
Join Date: Sep 2001
Location: Alma, AR 72921
Posts: 23
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Tachometer
I have the same identical problem with my tach. After about 3000 rpm it is erratic. I have replaced the points, condensor, coil and have also gotten a second used tach which does the same thing when installed. I am quite puzzled by the problem. My next attempt is to try to run the wire
from the coil to the tach. If anyone out there has any other suggestions feel free to let us know. 
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11-12-2001, 10:49 AM
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Join Date: Apr 2000
Location: Kentucky
Posts: 539
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My tach does this sometimes. I figure it's bad bearings in the tach and it needs rebuilt. However mine will do it in any gear when you get above 3k but only sometimes. So I figure it has to be, "IN" the tack itself.
__________________
1969 Porsche 912 <- Sold 
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11-12-2001, 10:58 AM
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Senior Member
Join Date: Nov 2000
Location: Stuttgart FRG
Posts: 2,307
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Hello
I think it is internall a cold solder spot developing problem after sveral years. there is also a condensor making trouble over the years. Pelican has something about that in the tech pages and also stocks Tachs in trade or rebuild them. But first always try the cheap things. Get a Dwell angle meter and hook it up on the tach wire. If it also jumps then hook up the tach and the dwell Meter as well to a other car to see whats up. Grüsse |
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11-13-2001, 05:07 AM
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Join Date: Jun 2001
Posts: 35
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Turns out to be a loose distributor. Thanks for the help.
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11-19-2001, 10:14 AM
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Registered
Join Date: Sep 2001
Location: Alma, AR 72921
Posts: 23
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Still need help.
In what way was the distrubuter loose? Was the bolt that held it in place loose or loose in another manner? Mine is still giving me problems.
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11-19-2001, 10:29 AM
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Join Date: Jun 2001
Posts: 35
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There are two bolts to the distributor. One that allows it to turn (for timing) and the other that bolts a metal clamp to the engine. It was the bolt that bolts to the engine. I could take the distributor and wiggle it back and forth. You might be having other problems with it though. The tach, as I understand, reads the pulses to the coil.
Dave |
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11-19-2001, 10:59 AM
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Registered
Join Date: Sep 2001
Location: Alma, AR 72921
Posts: 23
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Its fixed
Well all of you who said it was the points was right. It turns out I had a bad set of points or perhaps the wrong points. I replaced the points and the tach works great. I am suspicious of the possibility that I have the wrong distibutor on my car though? Is there a way to tell what type it is?
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11-20-2001, 07:44 AM
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