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Hey guys I'm going efi and need a place to mount some things there is a black vacuum can that has a small hose that runs through the firewall and a square silver box. Does anyone know what these are and if they are necessary?
Yup, they are necessary. Those cans are used for vacuum driven accessories, specifically, the vacuum trunk or, much more importantly, the AC controls. Losing this can will give you the undesired effect of, upon acceleration, putting your defrost on the floor for the duration of the acceleration, or other similar events.
The good news is that you can move this can if you need the real estate to somewhere else, just replace the vacuum lines with longer ones.
There are no ports on the left side. Ac doesnt work so it's not realy a issue it not working. Will be going with the vintage air setup to clean up the engine bay and also for the money I can have that setup brand new instead of working with old parts. So I may remove the can unless that'll mess with something else? If I can get a block off plate I was thinking about just deleting the evap and the whole hump that's there but not sure what all that entails since I have enough drive train stuff to deal with and I dont care to remove dash at this time.
We frequently get questions about "is this necessary"?
Seriously? Do people really think that GM added unneeded parts just to reduce profit? Common sense, people. A more reasonable question might be "what do these items do?"
We frequently get questions about "is this necessary"?
Seriously? Do people really think that GM added unneeded parts just to reduce profit? Common sense, people. A more reasonable question might be "what do these items do?"
I dont think anything was unnecessary in 1970 but there are multiple things that have been improved upon over the years and are no longer needed. For instance the regulator when you can get a alternator with built in regulator. Not trying to hack the car up just trying to make some room to update the systems and in the process a few things are getting trashed like anything that isnt needed with new parts being installed or things that have been improved upon and can increase reliability or just ease of driving. I appreciate your time posting here.
Well, if the car has an external regulator mounted on the firewall, its a safe bet that the alternator doesn't have one built in. Sure, it can be converted to use an alternator w/ an internal regulator. It can also be relocated (just be sure its bolted to a good ground). Isn't there a better place to mount the EFI box? Getting rid of that little voltage regulator isn't going to gain you much real-estate on that firewall.
Well, if the car has an external regulator mounted on the firewall, its a safe bet that the alternator doesn't have one built in. Sure, it can be converted to use an alternator w/ an internal regulator. It can also be relocated (just be sure its bolted to a good ground). Isn't there a better place to mount the EFI box? Getting rid of that little voltage regulator isn't going to gain you much real-estate on that firewall.
unfortunately with the evap box there is no extra room on the firewall but with the vacuum can removed or relocated and the regulator being removed I'll have more than enough to mount the box and coil while still being able to easily access the distributor
Last edited by 06turbosilverado; March 9th, 2020 at 09:18 AM.
unfortunately with the evap box there is no extra room on the firewall but with the vacuum can removed or relocated and the regulator being removed I'll have more than enough to mount the box and coil while still being able to easily access the distributor
convert to an internally regulated alternator. That will eliminate the need for the external regulator. As stated before, the vacuum can is needed for the air doors for the heater/A/C. I guess technically, they aren’t needed, you could learn to control the airflow with your right foot. 😁. There is suppose to be a check valve with a tee inline with the bulb. The one port by itself goes to manifold vacuum, the other ports go to the vacuum can, and too the climate control head. Without the check valve, there is nothing to prevent the vacuum from bleeding off into the manifold under heart throttle.
if you really need the room under hood, hide the tank inside the fender (easily bolted to the plastic wheelhouse) behind the passenger headlights on the core support, wherever you can find the space. As long as the vacuum hose is good and the tank doesn’t leak, there is no maintenance. Put it wherever you can find room. Or put the Vintage Air in, and “mount” the tank in the trash can.
convert to an internally regulated alternator. That will eliminate the need for the external regulator. As stated before, the vacuum can is needed for the air doors for the heater/A/C. I guess technically, they aren’t needed, you could learn to control the airflow with your right foot. 😁. There is suppose to be a check valve with a tee inline with the bulb. The one port by itself goes to manifold vacuum, the other ports go to the vacuum can, and too the climate control head. Without the check valve, there is nothing to prevent the vacuum from bleeding off into the manifold under heart throttle.
if you really need the room under hood, hide the tank inside the fender (easily bolted to the plastic wheelhouse) behind the passenger headlights on the core support, wherever you can find the space. As long as the vacuum hose is good and the tank doesn’t leak, there is no maintenance. Put it wherever you can find room. Or put the Vintage Air in, and “mount” the tank in the trash can.
thanks for the imput man. since I've had the car heat has been controlled by reaching in the glove box and manually operating the doors so nothing to new there lol
In that case, hook the linkage back to, connect the vacuum line without the tank and check valve. Then you can adjust the air from the comfort of the drivers seat, with no need to lean over! Feet cold? Apply a little more throttle. Windshield cloudy? Find a hill to coast down! If you and passenger are comfy, and the windshield is clear, hope light traffic! 😎. Maybe a shoelace could be used to move the air doors? MacGuyver would no doubt have some solutions
The Vintage Air kit comes with a block off plate for the firewall if you specify it for a factory air car. I know this because I have one on my '72 ragtop and it's a JOY having all that space freed up where the evap used to be. The VA system eliminates the need for the vacuum can entirely (at least as far having needed it for the factory system)
the voltage regulator can be completely removed if you install an updated internally regulated alternator. There is a simple wiring harness adapter you can separately buy (under $20) to block off the old wiring connector and connect your wiring to the updated plug that then goes directly into the new alternator. Did this as well early on for my car when installing a new engine harness.
The Vintage Air kit comes with a block off plate for the firewall if you specify it for a factory air car. I know this because I have one on my '72 ragtop and it's a JOY having all that space freed up where the evap used to be. The VA system eliminates the need for the vacuum can entirely (at least as far having needed it for the factory system)
the voltage regulator can be completely removed if you install an updated internally regulated alternator. There is a simple wiring harness adapter you can separately buy (under $20) to block off the old wiring connector and connect your wiring to the updated plug that then goes directly into the new alternator. Did this as well early on for my car when installing a new engine harness.
there's a LOT to do in swapping this system in for a factory AC but totally worth it - seats and console out, essentially entire dash (gauges, radio, glove box, etc) needs to be gutted to make room to work (which makes it a GREAT time to replace an original dash harness with a new one), old switch control panel and under-dash box are completely replaced by new VA components, all the original plastic ducts and air hoses ductwork are no longer needed, the complete under-hood evap core goes away as does the need for the intake-mounted heater valve, new condenser core and Sanden-type compressor replaces the old GM stuff. Kit comes with all hardware, firewall block-off plate (for factory a/c cars), under-hood brackets, refrigerant lines, condenser, compressor, under-dash a/c unit and new switch panel. Instructions are pretty decent and over-the-phone tech should be easy to get.
If you have a quadrajet I also retained my carb-mounted a/c idle solenoid switch.
The new compressor placement may require you to change your fan belts
the right inner fender well also has to come out to access one of the hidden firewall mounting bolts for the interior box
Also, the original dash speaker needs to come out to make more room for the new vent hoses to be run across the inside of the dash. Simple with the rest of it already gutted.
depending on how handy and/or ambitious you are, it could take a few days to a week or more to complete the swap.
I will say again - GREAT time to replace an original dash harness and the accessory harness that connects to it for the under-dash and switch lamps. Everything in the dash being out is really the only way you can do these and if the car is a keeper, should absolutely be part of the project while you can.
Last edited by 70sgeek; March 10th, 2020 at 02:20 PM.
March 8th, 2020, 04:45 PM
