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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: jhiggin on January 20, 2015, 07:35:31 pm

Title: 84 350 hei quadrajet vaccum simplified
Post by: jhiggin on January 20, 2015, 07:35:31 pm
So I'm working on an 84 350 hei quadrajet with manual trans. I'm looking to "delete" the egr and smog stuff. I know everyone's gonna probably crawl me about how I need egr and how it will run lean but this is an old farm truck not a daily driver so I just need to clean up the engine bay so I can get to other things on the motor. So what are the bare badics on vaccum lines I need and how can i plug the lines in the exhaust manifolds?? Any help please???
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: Stewart G Griffin on January 20, 2015, 07:51:46 pm
If it's an 84, then the vac line to the egr probably doesn't connect directly to a carb port;  It probably goes from a ported outlet on the carb to a TVS (thermal vacuum switch and then to the egr valve.   i suppose you could plug all the lines running to the TVS and remove the egr valve with a plate (may have to fab one).

i'm not convinced that an engine "needs" egr, but i'm going to reinstall mine so as not to take any chances.
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: jhiggin on January 20, 2015, 09:09:18 pm
Okay so your saying I can basically plug the outlet at the carb?
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: jaredts on January 20, 2015, 10:05:16 pm
The air injection lines can be cut short and bent over, but I have just bought brass pipe plugs before.  Minimum vacuum is brake booster, vacuum advance to distributor, the small line into the cab for hvac.  If you have a th350 trans it needs vacuum, and if you have cruise that you want to work there are a few more connections.  Pcv valve with a functioning breather is a must as well.  Everything else serves a purpose, but isn't necessary for basic functionality.
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: 1979cheyenne on February 17, 2015, 05:44:55 pm
The air injection lines on exhaust manifolds?
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: timthescarrd on February 17, 2015, 05:59:20 pm
Do you still have the computer controlled carb and ESC distributor?
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: Stewart G Griffin on February 18, 2015, 07:15:45 pm
Quote from: jhiggin on January 20, 2015, 09:09:18 pm
Okay so your saying I can basically plug the outlet at the carb?

Sorry for the slow reply, but yes you could plug the outlet(s) at the carb if you want to eliminate things underhood.

However, keep in mind that your particular quadrajet may have been *calibrated* to run with all those items and was designed to have all that air sucked thru those ports.  If you eliminate them then the carb *might* not run right and would have to be re-tuned at the very least and possibly re-calibrated.
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: Irish_Alley on February 18, 2015, 11:07:24 pm
what about the vacuum for the heater blender doors?
Title: Re: 84 350 hei quadrajet vaccum simplified
Post by: jim.clark.52687506 on February 19, 2015, 01:09:06 pm
I just bought a 84 K2500 with a 350 and auto Trans I so want all that cap off of my motor too. It runs ruff now. I  just ordered a complete tuneup kit from Jegs. I'm hoping I too can eliminate all the excessive hoses and whatnot that are flopping around loose/disconnected under the hood. any suggestions welcomed  this is going to be a goof off truck 50/50 farm/dear lease town driver on the weekends....