BrianAmeliom

Hi, I'm new to the forum but I have a question. I have a 1966 Impala SS with a 396 BB. When I ran the numbers on the heads, they are 69. I purchased an Edelbrock intake manifold (EDL-7562) but when I installed it I can see open areas on the heads where the choke coil would heat up from on the factory intake. I see these openings and I'm starting to think I purchased the wrong intake manifold. I'm attaching a picture of the factory intake manifold (sitting on the floor) and the new manifold installed with the open head ports exposed to the world. I think I have the wrong intake installed....
I'm thinking when I start the engine we will have a loud exhaust sound coming from the engine and it will be smoking exhaust on the new intake and carburetor...

Thanks in advance!
Brian

BrianAmeliom

from the link below:

All production big-block heads had an exhaust crossover passage between the two pairs of siamesed intake ports. The casting cavities above and below the center exhaust crossover are blind cavities that don’t connect to anything. Some aftermarket intake manifolds don’t cover the upper opening, which does not cause any problems.






https://www.cartechbooks.com/blogs/t...rbigblockchevy

The Heater

Hi, Brian:

The post above is not correct. I own a Big Block, OEM in my K2500 Chevy truck I have owned since new in 1994, and it DOES use that pass through. So it is NOT a blind port. Based on your information, you have a Mark IV block, which would be all 396 blocks. They have different oil passage sizes and the oil gallery is smaller than on newer blocks, PLUS you use that exhaust pass through.

If the OEM manifold featured that pass through then you MUST use a manifold that is compatible. Edelbrock makes a Performer manifold that I am using with their Aluminum 118cc heads specifically designed with the pass through port on both the heads and the manifold. I am using the stock throttle body injection but I have a roller cam and valve control system and custom roller rocker assemblies. I suggest that you CALL tech support for Edelbrock. Email you don't get to have an actual conversation in case you need to clarify things.

As additional validation of my comment, it is abundantly clear from your photo of the ports on the old manifold that it has exhaust carbon deposits. So you cannot use the manifold you show as a replacement. Again, please call Edelbrock tech support. Don't use email because some nit wit may send the wrong information.

BrianAmeliom

Thanks for your post. The old manifold made me think that it was not a "blind" port but when I read that posting I thought maybe I was wrong. You're right, I can call Edelbrock and ask them to help me.
Thanks again for your post!
Brian