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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Wyomingite on February 21, 2019, 09:45:42 pm

Title: Vacuum connections
Post by: Wyomingite on February 21, 2019, 09:45:42 pm

Looking for some help on what the two ports are for with question marks in this picture. Mine currently has them both capped off. Along with the one marked “emissions” That is also capped off. Would that go to the emissions can on the radiator support?
Also, I’m hearing it’s best to run the distributor to the manifold vac. On drivers side and the TCC switch to the ported vac on the passenger side. (https://uploads.tapatalk-cdn.com/20190222/9f1c8648ad9253ccb1327b41e89c5446.jpg)


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Title: Re: Vacuum connections
Post by: Irish_Alley on February 22, 2019, 07:18:25 am

depending on what your truck has set up but my mud truck with no emissions i have brake booster  which should be manifold vacuum, pvc which should be manifold vacuum and distributor which again should the one marked "cap" manifold vacuum (for best performance, if you want better emissions you have it to ported)

but your trans should be hooked up to manifold vacuum also. im not sure about your carb but if you have the engine running put your finger over the port and see if theres vacuum

Title: Re: Vacuum connections
Post by: Wyomingite on February 22, 2019, 08:41:14 am

Yeah all emissions equipment is removed.
So just the basic items.
I’ve read conflicting stories of weather to use ported or manifold vacuum for the tcc switch. With manifold vacuum, wouldn’t it be trying to lock the converter at idle?


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Title: Re: Vacuum connections
Post by: Irish_Alley on February 22, 2019, 09:15:45 am

what trans do you have?

Title: Re: Vacuum connections
Post by: Wyomingite on February 25, 2019, 04:55:45 am

Trans is a 700R4


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