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Discussion Starter · #1 ·
I think mine is missing! Here is what I have, '76 280z, mnfg 7/76, manual trans, non calif. Doing replacement of sensors at the thermostat housing and noticed a white and black wire with bare ends twisted together (shudder). Looked in the service manual and I think the wires go to a vacuum switching valve mounted on top of the thermostat housing...which my z does not have (sigh). The engine ran...barely when I got it, so I am doing a few other things also. What effect does not having the vacuum switch have...is it something people tend to get rid of?? From the manual, this would seem to mess up the advance and retard functions, The distributer vacuum is plumbed with the carbon canister at the moment. Any help is appreciated, Thanks
 

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I'm gonna take a guess here on that one.
There is a sensor located on the thermo housing that controls
the vacuum advance switching between the retard [email protected]/ advance [email protected] when warm or cold. I believe it's only for auto transmission which have dual pickup coils
in the distributor. The manual has one pickup.
This was done for emission purposes.
You can probably cap and ignore
 

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Discussion Starter · #3 ·
> I'm gonna take a guess here on that one.
> There is a sensor located on the thermo
> housing that controls
> the vacuum advance switching between the
> retard [email protected]/ advance [email protected] when warm or cold. I
> believe it's only for auto transmission
> which have dual pickup coils
> in the distributor. The manual has one
> pickup.
> This was done for emission purposes.
> You can probably cap and ignore

Thanks Ron, yes it does control the advance, the service manual says for manual transmission models (except calif). My distributor is the dual pick up. My concern is that with vacuum applied to the distributor all of the time, the spark timing is always retarded??? According to the book, this should only happen when in 4th gear, controlled by the switch on the transmision. If this can be deleted, I would like to know how to do it correctly...and not leave twisted bare wires exposed.
 
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