Hi All,

I have a 71 Nova SS, and I'm transplanting a big block into it. I found that the big block heater box, in the engine compartment is different. It allows the heater core hose inlet/outlets to come out of the middle of the box, vs the ends coming out on the firewall.

Have anyone here ever held both boxes in their hands to compare them?

Are they actually the same with the BB one simply having holes in it? Or is the profile different as well?

I was wondering if I could just take mine and cut the holes in it and purchase a BB heater core and install it that way.

For that matter, does anyone know of the 69 or 70 big block cars still have the holes in the firewall for the small block heater hose outlets? Or were they just plugged?

Thanks.

-Russell

So far as I know it is the same heater box cover (you have to buy a patch kit to replicate the same plugs the factory used. The heater cores are entirely different in size and where the tubes exit the heater box.

Big Dave

here's some BBC heater box info: http://www.chevynova.org/BigBock.html

Thanks Guys!

Actually, that's a great link as I was wondering what was different on BBC engine mounts and SBC mounts. I thought it was just height, and didn't realize it moved them to the left.

i believe the transmission crossmember does the same...

The heater box cover is identical it just has holes in a different spot. I drilled new holes in my box and made some patches to fill the original 6 cyl holes. The heater cores are different but I've seen people flip the small block/6 cyl cores over and use them that way.

Don't forget the other end of motor mounting system with the transmission. You need a special BBC transmission cross-member with the holes offset one inch to the passenger side.

Big Dave

I'm wondering what would be the outcome if I just used the small block stands/trans mount.

Would it be too close to the steering box?

I think I'll give that a shot at simply cutting out my stock heater box, and plugging the holes. Thats funny about the heater core! I wouldn't have thought to turn it upside down! Of course, Autozone has the heater core for BBC w/out AC for $26 so I'm going to order it anyways. We'll see how close it comes to my original SBC setup