My old stock manifold had water passages in the rear of it. The block has water ports in the rear. The edelbrock performer EPS manifold I am about to install has no rear water passages. I had it on my old '66 283 for a long time, which also has water passages in the block. WHY IN THE WORLD does edelbrock not put rear water passages? I have a hard time understanding how the coolant will still flow? Thanks, James PS: there is a bunch of mineral buildup and gunk in the water ports in the block, and a bunch of carbon chunks built up in the exhaust crossover.. yuck that old manifold is HEAVY!!!!