72 Intake has rear water passages blocked

[brown7373]

I am installing a crate 350 to replace my original 350 that crapped out. The original intake has the heat crossover blocked, which I understand is fine, especially with me living in Florida.

But the rear water passages in the intake are also blocked, filled with some kind of solid filler.

I have owned this truck since 2003, driven nearly 80K with zero problems. It never overheats, even with A/C on in traffic in the middle of summer.

Is there some reason the rears are blocked? If it ain't broke, don't fix it, but why was that done?

[geezer#99]

It’s because there’s no water flow there.
Water is pumped in the front of the block, flows to the back thru the block and back thru the heads to the front.

[ray_mcavoy]

Yes, that is perfectly normal for the rear of the intake to be blocked like that. As geezer#99 described, with the way the coolant flows through the engine, there is no need for any side-to-side connection back there. And the only reason the cylinder heads even have coolant ports back there is to make the heads interchangeable, eliminating the need for left or right side specific castings.

[brown7373]

Thanks for clearing that up. I wondered about it, but since it was never an issue I wan't concerned. But now I know why it is that way.