[jrat69]

While taking out my big block I broke one of the metal heater core tubes off the firewall. Is it difficult to swap a small block core to a big block core? I'll be more carefull next time since the heater core was no fun removing! rats

[Everett#2390]

It can be removed relatively easily.

1. Remove glove box and its door, four screws across the hinge.
2. From engine side, remove six speednuts. The last and seventh one is on the other side of the blower and does not need to be removed.
3. Place plastic sheeting, large piece to cover the carpet from the firewall to the seat to the kickpanel to draped over the rocker panel to the ground. Suggest to have 2-3 inches of sides to hold coolant.
4. Reach up with hands on the defrost extension and right hand side of heater and gently, but forcefully pull heater box to the inside. There is sealant around the heater box.
5. Once box is loose, turn box on its rear side and this will expose the core.
6. Remove screw and clamp with 5/16 nut driver and pull core out of box.
7. Installation is reverse.
8. Operate heater controls to make sure all the cables work their intended function correctly.

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Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"

[Codi]

If you want to swap from a small block core to a big block, you will have to modify teh "blower box" in teh engine compartment. The BB core exits the tubes near the middle of the box, where the SB core exits the tubes near the center of the engine compartment. While everything is out, measure and mark the exit location for the BB core tubes in the blower box. Drill the holes for the tubes a bit larger than the tubes to give them wiggle room. Get a new seal kit for the heater box if needed and get an "adapter" for the BB tubes. This is a metal piece sold by the resto companies that covers the exit holes for the BB tubes. Replace any bad seals while everything is out. I got my BB core from Autozone for around $30.00. Some modification of the spring clips holding in the core is required for the BB core. This should be all that is required to switch heater cores.

[RaceHome]

Once you swap to a big block heater core, you will next complain about having to replace it. The BB heater core is SOOOOOO much easier to replace. I don't know what GM was thinking when they didn't just use the big block heater core on all of their first gen F-bodies!

The swap is worth it.

Good luck,
Tony Huntimer
RaceHome.com

[This message has been edited by RaceHome (edited 01-07-2003).]

[CFunK]

Everett,

So you are saying that to remove the core I can leave that last NASTY bolt alone and remove the core from the inside and not worry about disturbing the caulk on the box at the enginge side of the firewall?

I assume the inside box will pull back enough to allow the core to come out, correct?

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-Funk
My '67 RS

[jrat69]

Thanks for all the info. When removing the heater core I partially removed front quarter panel to access that nasty bolt near the outside firewall. Did not know it could come out the glove box. Next time I will ask you guys first. Looking more into swaping from small to big block heater core. Thanks again!

[Everett#2390]

CFunk,

That is correct. The changeout can be done inside the car. And there is just enough slack on the cables for one to pull and turn the box around to get the core out.

I agree with Tom, BB cores/set-up are much easier to work on due to their location on the firewall. Why didn't GM chose this route in the beginning?

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Everett "OBJECTS IN THE MIRROR APPEAR QUICKLY UPON RAPID DECELERATION"

[DjD]

If you plan on using the BB core you also need the BB cover under the hood and that requires getting to that nut behind the blower motor.

[JWA]

Dennis,

You can get the cover plate(19.95) from rick's first gen and just drill the holes in the SBC heater cover as mentioned above. Probably be easier if it was removed from the car as you said though.

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Jeff
69 SSRS 396(roller 427 )
My Chevs