I am planning to redo my heater core and was wondering. Do I get to from inside the dash? The car has AC or do I get to from the casing that sticks out from the back passenger side  of the engine bay? I have the engine out.

From the dash side.  You have to remove the lower dash on the passenger side.  Also, you need to remove the hoses and the insulator (if still there) where they go up into the heater core from below.  When removing the bolts that hold the plenum divider (think that is what it is called), watch for one trick bolt that goes all the way through the firewall and has a nut on the outside (this one drove me crazy for awhile).  Be very careful pulling the heater core up and out.  The piping is soft and can break off if not handled gently or has a little too much corrosion.  Also get one of the gasket kits to put everything back together with (mine came from Zip).

If you search on this subject, somebody posted pictures and a description of the procedure a year or two ago and it is very helpful if you haven't been through it before. 

Good luck.

I'm with ya man. My pass. windshield fogged on me the other day. It did it again this morning. Looks like another winter project.

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Click on images for Before and After pics!

Hey I took the pad dash off and looks like I have to take the gage panel also. I tryed posting pictures and screwed that up. It looks more involved then just the dash pad.

Dave,

Check this out (click here) for a look at replacing the heater core in a '70.  This was in an old thread (found using the Search function) and posted by a former member.

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Jim Olson 

"The Toys"...!!!  Save the Wave!

Where I've been in a Corvette...!!!

Hey thats a good thread to have thanks. To take the Evaporator and blower housing from the engine bay are there bolts from inside the car to undo?

To be honest I don't know.  I don't have A/C on "The Toy" so I'd have to look at the AIM to see the detail. 

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Jim Olson 

"The Toys"...!!!  Save the Wave!

Where I've been in a Corvette...!!!

Norsky, great thread wish I would have had it when I replaced mine. Would have been a lot less cuts and grey hair. Thanks

Dave,

Looking from the engine bay there is good size screw on the lower right hand corner. That looks like it unscrew from the inside. I wondering if I should go any deeper with it? Something tells me do it now. I need to put my gas tank back in before I take this on. I hate have to many things apart. Starting in march the vette goes to the shop for the engine install so the heater core has to be done. 

OK I have four bolts out is there a 5 one? The box will not come out. The center dash vent is still there does this have to come out? There are a lot of cables on the driver side of this I dont really want to mess with that.

There seems to be a nut in between the AC box and back of the firewall> It looks like I have to take the AC box off to get to that one nut. Is that the case. The nut is the upper left one facing the box from inside the car. Is this a another Buba job?

Here is a update. In my car you can not take out the heater box without taking off the evaporator box in the engine bay. Is that normal for all AC 70 Vetts? So the heater core looks like it had a small leak which might explain why there was a cut off valve switch on the heater hose. I spent a good amount time cleaning up the heater box. I order a heater core from Napa and today I will order the Heater box gaskets. I did take enough pictures I hope I can put this back in.