Got a question guys -
After replacing a leaking intake manifold gasket something occurred to me: The old intake gaskets had blockoff plates in both rear coolant crossover holes. Several hours after torquing the manifold down with new gaskets, I realized that the new gasket set didn't include the blockoff plates, and I didn't reinstall the old ones.
Now, I have a few questions.
1) Will this cause any actual problems?
2)Why were these both closed off when one of my heater hoses plumbs into the crossover?
3) Has anyone else found this on their engine?
Thanks in advance for any replies.:hail:

 

shouldn't make any differance

 

What's the purpose of the block off in the first place? Wouldn't it cool better with them open?

 

That's what I would think. The engine was rebuilt not long before I bought the car, I have a feeling it wasn't always blocked off. Like I said before, I had a heater hose that basically went nowhere. Doesn't make sense to me.

 

Very few SBC intakes use the rear coolant ports. Most, the manifold is a solid piece of metal over the rear ports, blocking them off completely. Some have a heater hose coming off the rear, pass. side head from a fitting in the intake, but this is rare.

Having gaskets with the open holes at the back won't hurt anything- they will still seal off the coolant passage if properly installed.

Reason for rear coolant passages in the heads? Simple, SBC heads are all interchangable from side to side so you never know which way is front, so they put coolant ports on both ends!

 

While I didn't "think" it would hurt anything, the older I get the less I rely on what I "think" I know. And you're right, the last SBC I had was blocked in the intake, forgot about that.

 

So what would happen if you opened up the rear coolant passage. The edelbrock intake I am soon getting has the rear coolant passages as well as the front so I was just going to leave them open. Any advantages or disadvantages to this?

 

I really think it will be OK to have both crossovers open, I mainly posted this to make sure I wasn't missing anything.
I'm not sure it makes a lot of difference either way as far as any advantage/disadvantage to having both open.

 

connect the rear water outlets with the front at the thermostat housing. Increase coolant flow in the heads.. also causes some constraints on fuel line routing and carb linkage .. I just connected the two back crossovers on my modded vic-jr intake.. Im not sure it helps much.. but 400s need all the cooling they can get.