I'm trying to pull the carbs and intake manifold off a 1970 144S parts car and I can't seem to get the intake manifold off (everything is original with dual stromburgs). I took the four 13mm nuts off the studs holding the upper part of the intake manifold on, then took off the two 13mm nuts under the manifold that appear to secure both the intake and exhaust manifold. With these 6 nuts taken off I can't budge the manifold to pull it off the motor. Did I miss a nut somewhere? The exhaust and intake manifolds are seporate, right? Do I have to loosen the entire exhaust manifold too? Maybe it's just really stuck on there? I used a large flat-head screwdriver and hammered it in as a wedge between the motor and manifold where the gasket is, but it still didn't budge. How do you get this darn cast iron intake manifold off?