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SPTom
Samba Member
Joined: December 30, 2021
Posts: 26
Location: São José dos Campos --SP Brasil
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 Posted: Thu Dec 30, 2021 10:36 am Post subject: SP-2 Tachometer |
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Hi everybody, Long-time lurker, first-time poster. I have an SP-2 and the tach has never worked properly. I'm digging into it to see what I can do. I've got it hooked up to Ground, +12V, and coil, but when I turn the car on (engine off), it jumps to 1000RPM. At idle, it's reading 2000RPM. Which makes me think it's either reading 1k too high or there's something else I missed. Anyone witness something like this before? Thanks.
In this photo, red nut gets continuity to coil, brown nut gets +12V, and the case connection gets ground.
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MrGoodtunes
Samba Member
Joined: May 14, 2012
Posts: 851
Location: South Florida
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| Posted: Fri Dec 31, 2021 7:18 pm Post subject: Re: SP-2 Tachometer |
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| SPTom wrote: |
| ... when I turn the car on (engine off), it jumps to 1000RPM .. |
Electronic ignition?
If not, try having ignition switch in ON position with engine not running; and see if the tachometer shows any difference between when points are open versus closed, by using a wrench to turn crankshaft far enough to operate points.
Coil balast resistor? Correct coil terminal? |
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SPTom
Samba Member
Joined: December 30, 2021
Posts: 26
Location: São José dos Campos --SP Brasil
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| Posted: Wed Jan 05, 2022 11:58 am Post subject: Re: SP-2 Tachometer |
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| MrGoodtunes wrote: |
| SPTom wrote: |
| ... when I turn the car on (engine off), it jumps to 1000RPM .. |
Electronic ignition?
If not, try having ignition switch in ON position with engine not running; and see if the tachometer shows any difference between when points are open versus closed, by using a wrench to turn crankshaft far enough to operate points.
Coil balast resistor? Correct coil terminal? |
Hi thanks for the good questions. It originally came with points but they have been replaced with electronic ignition somewhere along the line. I didn't think about if the coil had a ballast, but since you brought it up, I checked the voltage and it seems not to have one (same voltage whether negative post is floating or grounded). Did it originally have one? Not sure. Based on the year of manufacture, 1973, I think it could be either way. Tach is connected to post 1, which is the negative post. |
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