61 270hp 2x4 intake manifold

[Mike B.]

Still learning about vettes by reliving my youth. Having just broke #1 cyl intake valve and spring (don't know which went first) and taking apart things I found the heat shield laying in belly of block and the 4 rivets. I did find the answer to the shield in the threads (thanks to all) but any idea or is it common for this intake valve to break. Also, why is the manifold not ported for the last exhaust passages???? Just curious?

[John H.]

Re: 61 270hp 2x4 intake manifold

Also, why is the manifold not ported for the last exhaust passages???? Just curious?

Mike -

The rearmost port on the cylinder head on each side is a coolant passage, not an exhaust passage - it's only there so it's functional as the front coolant crossover passage to the intake manifold on the other side of the engine (so the same cylinder head can be used on each side). All Chevy small-block intake manifolds block off the rear coolant port on both cylinder heads.

[Mike B.]

Re: 61 270hp 2x4 intake manifold

As always you guys are the greatest source of CORRECT information. thanks, mike