I recently danced around with whether to use hot water or hot exhaust gas for manifold heat and opted for exhaust gas heat.
Theres no question that some sort of manifold heat is necessary for "optimum" performance of these engines so which ever method you use will be beneficial.
In any case, a leaking intake manifold is bad news especially when it's in the casting. I don't know how you'd find and seal the hole that's leaking up into the fuel/air passage so basically the intake is toast as it will cause problems with leaking exhaust gasses into the intake also.
Tom Langdon has a tech article on how to seal up a leaky heat chamber but the holes are casting holes on the bottom of the intake and are easy to get to. He says they aren't sealed properly from the manufacturer. He doesn't indicate the make tho.
It's bad to hear of such problems in the casting of these parts.
My Fenton dual intake doesn't leak (thankfully) so theres hope you'll find a good one.
Good luck
Dave
