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Ed Bradshaw


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Hello, looking for "SWIRL CONTROL VALVE CONTROL VACUUM CHECK SWITCH" for a 1984 NISSAN 720 Z24. Item is identified as SPDB28-58. My pickup failed the California smog test and the mechanic told me to replace the switch. The Carbon Monoxide was too high indicating rich mixture. Problem is I've had a very hard time finding one. Please help if you can. It hurts to think I will need to scrap my Dad's truck if I can't pass the smog test by March 31 2020.

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Thank you for posting! I will take images as soon as I can and post them here. In the mean time this is what the part looks like (example). https://www.ebay.com/itm/Swirl-Control-Valve-Control-Vacuum-Check-Switch-Nissan-SPDB28-111-22360-2Y900/143520447557?hash=item216a7c3c45:g:jkMAAOSwFmtdVbJx My defective one has SPDB28-58 marking.

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Yes, it looks exactly like that but is used to turn the exhaust coil off under heavy load. There is a second that senses vacuum for the fuel cut system. There is no swirl control valve on the 720. Your 720 is older than your mechanic, they don't teach carburetors to new mechanics.... he don't know. YOU know as much about your 720 then he does, MORE even. The swirl valves are inside the KA series EFI engines and are in the intake runners and induce swirl at low speeds for better mixture distribution.



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OK, thanks for putting me on the right track. I have the original Service Manual now. Viewing "Engine and Emission Control System Diagram B for California" Section EF & EC - 9.  I have M/T model with manifold vacuum. This explains why I have only found ported vacuum switch for sale in part stores or online. I need to find a Vacuum Switch (for full throttle) that uses a vacuum line to the manifold. Do you or anyone else reading this thread have a suggestion as to where I can find this type of part? 


Thanks in advance.


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