My Buick 263 straight eight seems to have developed several leaks at the exhaust manifold over the winter. The car resides in a heated garage and I have driven it only a few times since the weather has changed and I have noticed that I have some new leaks that I did not have before. My understanding is that these engines are notorious for the exhaust (and intake) manifolds expanding and contracting at a different rate then the block. My heat riser is stuck all the way open and always has been. Engine has about 40K on it. I have plans to put headers and change the intake to compound carbruation (have one) but not until this winter cause I just want to drive it this summer. Currently I have no known intake leaks just exhaust leaks. My question is....can the exhaust leaks be temporarily remedied or reduced without tightening or unbolting it the manifold? I was thinking of some sort of malleable material that could be hammered or inserted in the gap. Would love any thoughts from the crowd.