New 1979 Chevy K10 stepside question

[natep7]

I just bought this truck and currently restoring it back to original (slowly). The motor is not the factory but is out of a 79 chevy. The engine was modified with a comp cam, roller rockers, edelbrock intake and Holley double pumper carb. I recently got all the dash lights and gauges working and now time to move on the engine bay. I noticed all the ac/heat parts were there and the blower motor is working. The question is they never installed the AC back on this truck, so I wanted to buy a new compressor to install BUT from my understanding this truck needs the vacuum to run the vent/defrost. My carb doesnt have a vacuum port if im not mistaken so what would i need to get this working?

You must be registered for see images attach

 

[natep7]

Current engine bay picture.

You must be registered for see images attach

 

[Old77]

Really cool project! I love the stepside K10's

 

[Craig 85]

It should pull vacuum off the intake, look at the lower part of the diagram. This is for a fuel injected truck. There are some differences for 79-84. I know my 79 K15 had different vacuum step up for the selector switch on the dash and the dryer was set up differently than my '85. There should be a spherical ball (vacuum tank) on the driver side firewall and the fender.

You must be registered for see images attach

 

[1987 GMC Jimmy]

It needs vacuum to mode select period. It should be pulling vacuum for the cruise modulator if so equipped and HVAC mode selection of a port on the back of the intake, and that splits off to go the two separate ways at a one way vacuum check valve. The one that goes in the direction separate to the HVAC side will go to a vacuum storage tank. The diagram gives you an image of what to look for when you buy parts. Do you know what compressor you need? A6s were used until 1984, and I think the R4s ran concurrently to them before ‘85.

 

[Craig 85]

1979 should have an A6. Here's what my '79 looked like just before I sold it.

It needs vacuum to mode select period. It should be pulling vacuum for the cruise modulator if so equipped and HVAC mode selection of a port on the back of the intake, and that splits off to go the two separate ways at a one way vacuum check valve. The one that goes in the direction separate to the HVAC side will go to a vacuum storage tank. The diagram gives you an image of what to look for when you buy parts. Do you know what compressor you need? A6s were used until 1984, and I think the R4s ran concurrently to them before ‘85.

If you look in his first photo, you can see the cruise control just IFO the master cylinder on the fender well. It has the set up for the speedo cable. The one in photo #3 is for an '83 Cutlass. My '79 had an aftermarket C/C so I don't know how this factory set up is plumbed.

You must be registered for see images attach

You must be registered for see images attach

1983 Cutlass

You must be registered for see images attach

 

[1987 GMC Jimmy]

Oh, yeah. I guess I didn’t look closely enough at the picture of his engine bay. I meant transducer, by the way, not modulator. I used to have a good diagram of this setup, and it’s somewhere on the forum, but it’s not on me. I found this, but it seems vague.

You must be registered for see images attach

 

[Frankenchevy]

Cool looking truck!