An easy question here. I am putting a big block in a small block 69 coupe. Can I use the small block heater core.

Wrooster

Big Block moves the inlet and outlet towards the passenger's fender. Gives a bit more room since big block engine mounts shift the block over an inch or 2.

So to do it correctly you will need a new heater core and cover.

There is nice article from Classic Industries on what you need to change out going from SB to BBC:
http://www.classicindustries.com/review/tips/tip016.htm

darn double posts

Thanks for the link, I should have been more specific. I know the heater core and box are different on the big block, has anyone used the small block set up, if so where there any problems.

Wrooster

The reason they are different is because the passenger side valve cover on a big block sits VERY close to the firewall right where the heater hoses come out on a smallblock equipped car. You can use a smallblock outer heater box & just cut the holes for the bigblock heater core & add the plate that surrounds the heater tubes but you do need to swap to a BB heater core. You will also need to swap the frame mounted motor mounts. Trying to cut corners will only cause you to pull your hair out when nothing fits properly. As me how I know.....

Mark has it right. It isn't that much green for the new heater core, cover and mounts ($200 or so). Without the motor mounts you will probably run into issues with the exhaust manifold/headers hitting the steering box. Big Blocks take up a lot space. It very much worth it to get everything to look good yet alone fit at all.

Thanks for the posts. I have the engine mount stands for the big block, was just hoping to not have to pull the passenger fender to get at the heater box. It seems everytime I do pull the fender out, no matter how careful I am I always wind up with an alignment issue. Guess I have no recourse If I want to add the big block. Since I already have the motor and trans I guess my decision is made. I have original big block motor mount stands and the motor has the original motor mount brackets. Now the guy that built the motor originally intended it for a Chevelle, will the Chevelle motor mount brackets work for the Camaro. The motor is a 73 hi-po 454 block. And does anyone have any recommendations for the motor mounts. I have heard guys having problems with the after market mounts.

Thanks for all the assistance.

Wrooster

I've done it, but wouldn't recommend it.

Hello , You can re fab the small block heater box .Just order the support bracket and gasket for the heater hose to box . Use that as your template to cut out the holes. Place the bracket at the edge where there is that v channel near the fan area .This is where you place the bracket ,trace the holes and hole saw them out .As to the big block use the small block mounts that that will move the engine center in the car and back towards the fire wall . This will take the weight off the front of the car ,and help launching abilities.Yes and now the bad news you have to fab the heater box in this area the back part of the head will not clear the box ,it will have to be knotched . if you need pics i can send them ,ICAN BE REACHED AT MTALP50@COMCAST.NET